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3" MACROGLIDE FOCUSERS

2" MASTERGLIDE FOCUSERS

2" MICROGLIDE FOCUSERS

3" MacroGlide [OMEGA & ALPHA] QUICK REFERENCE Guide

3" MACROGLIDE Focuser [manual control] OMEGA Focuser OMG1, includes all features of the following motorized focusers, except no motor drive. Upgradeable to motor control. A secondary focuser with 1" of tube travel for SCTs, etc. Custom tube travel lengths available by special order. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).
AUTO-FOCUS 3" MACROGLIDE Focuser [Stepper Motor] OMEGA Focuser OMG2 (AUTO-FOCUS electronic hardware package available at AUTOFOCUS link), includes Robo-Focus stepper motor and hardware mounted on OMEGA. Purchase stepper motor interface hardware and software separately. A secondary focuser with 1" of tube travel for SCTs, etc. Custom tube travel lengths available by special order. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).
3" MACROGLIDE Focuser [DC Servo Motor] OMEGA Focuser OMG3, includes DC servo motor and hardware mounted on OMEGA, VSI Dual-Control hand paddle and wall-wart 120vac power supply (purchase 12vdc car lighter adapter separately). DC servo motor has 6' cable with 1/8" phono plug to connect hand paddle. A secondary focuser with 1" of tube travel for SCTs, etc. Custom tube travel lengths available by special order. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).
Both above motor packages for 3" MACROGLIDE [OMEGA] Focuser OMG4 (AUTO-FOCUS electronic hardware package available at AUTOFOCUS link), includes stepper and DC servo motors, VSI Dual-Control hand paddle and wall-wart 120vac power supply (purchase 12vdc car lighter adapter separately). VSI [interchangeable] motor mounting hardware installed on Robo-Focus stepper motor and DC servo motor. A secondary focuser with 1" of tube travel for SCTs, etc. Custom tube travel lengths available by special order. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).

All MACROGLIDE Focusers REQUIRE Docking Converters and Moving Tube Output Adapters
These are the same Docking Ring Insert Adapters (3.8" ID) and Moving Tube Output Adapters (3.1" ID)
used in the New TOADLOADERS. You can simply click here, or go to the FOCUSERS Link to see these items.

3" MACROGLIDE [manual control] ALPHA Focuser ALF1, includes all features of the following motorized focusers, except no motor drive. A primary focuser with 5" of tube travel for refractors, etc. Upgradeable to motor control. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).
AUTO-FOCUS 3" MACROGLIDE [Stepper Motor] ALPHA Focuser ALF2, (AUTO-FOCUS electronic hardware package available at AUTOFOCUS link), includes Robo-Focus stepper motor and VSI hardware mounted on ALPHA. Purchase stepper motor interface hardware and software separately. A primary focuser with 5" of tube travel for refractors, etc. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).
3" MACROGLIDE [DC Servo Motor] ALPHA Focuser ALF3, includes DC servo motor and hardware mounted on ALPHA, Dual-Control hand paddle and wall-wart 120vac power supply (purchase 12vdc car lighter adapter separately). DC servo motor has 6' cable with 1/8" phono plug to connect hand paddle. A primary focuser with 5" of tube travel for refractors, etc. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).
Both above motor packages for 3" MACROGLIDE [ALPHA] Focuser ALF4 (AUTO-FOCUS electronic hardware package available at AUTOFOCUS link), includes stepper and DC servo motors, Dual-Control hand paddle and wall-wart 120vac power supply (purchase 12vdc car lighter adapter separately). VSI [interchangeable] motor mounting hardware installed on Robo-Focus stepper motor and DC servo motor. A primary focuser with 5" of tube travel for refractors, etc. Does not include docking converters or output adapters (see FOCUSERS link, 3" TOADS link).

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2" MasterGlide QUICK REFERENCE Guide

MasterGlide [Manual, no motor] Focuser M1 (picture not shown) Basic rock-solid focuser like the ones below, but with two focus knobs and nothing else. No motor control. No Tri-Focus (micro, median & macro) manual knob control. No DC servo (analog) or stepper (digital) motor control. NO Analog or Digital RO.
MasterGlide [Manual, no motor] Focuser M2 (picture not shown) Same as M3 below, but no motor control. Includes Tri-Focus (micro, median & macro) manual [knobs] control. No DC servo (analog) or stepper (digital) motor control. NO Analog or Digital RO.
MasterGlide [DC Servo motor] Focuser M3 with Dual-Control hand paddle and 120vac wall-wart power supply (optional 12vdc car lighter adapter, below). NO Analog or Digital RO. DC servo motor has 6' cable with 1/8" phono plug to connect paddle., includes Tri-Focus (micro, median & macro), DC servo motor and hardware mounted on M3.
AUTOFOCUS MasterGlide [Stepper motor] Focuser M3A (see FOCUSERS link, AUTOFOCUS link for electronic hardware packages), includes Tri-Focus (micro, median & macro), Robo-Focus stepper motor and hardware mounted on M3. Purchase stepper motor interface hardware and software separately. No Analog or Digital RO.
Both above motor packages for MasterGlide Focuser M3B (see FOCUSERS link, AUTOFOCUS link for electronic hardware packages), includes Tri-Focus (micro, median & macro), VSI [interchangeable] motor mounting hardware installed on Robo-Focus stepper motor and DC servo motor with Dual-Control hand paddle and 120vac wall-wart power supply (optional 12vdc car lighter adapter available below). NO Analog or Digital RO.

MasterGlide [DC Servo Motor Analog Reference] Focuser M4, includes Quad-Focus (micro, mini, median & macro), DC servo motor and hardware mounted on M4 with Dual-Control hand paddle and 120vac wall-wart power supply (optional 12vdc car lighter adapter). DC servo motor has 6' cable with 1/8" phono plug to connect paddle.
AUTOFOCUS MasterGlide [Stepper Motor Analog Reference] Focuser M4A (see FOCUSERS link, AUTOFOCUS link for electronic hardware package), includes Quad-Focus (micro, mini, median & macro), Robo-Focus stepper motor and hardware mounted on M4. Purchase stepper motor interface hardware and software separately.
Both above motor packages for MasterGlide Focuser M4B (see FOCUSERS link, AUTOFOCUS link for electronic hardware package), includes Quad-Focus (micro, mini, median & macro), VSI [interchangeable] motor mounting hardware installed on Robo-Focus stepper motor and DC servo motor with Dual-Control hand paddle and 120vac wall-wart power supply (optional 12vdc car lighter adapter).

*M4s have an extra 3/4" profile to accommodate the clearance needed for the analog read-out.
MasterGlide [DC Servo Motor Digital Reference] Focuser M5, includes Quad-Focus (micro, mini, median & macro), DC servo motor and hardware mounted on M5 with Dual-Control hand paddle and 120vac wall-wart power supply (optional 12vdc car lighter adapter). DC servo motor has 6' cable with 1/8" phono plug to connect paddle.
AUTOFOCUS MasterGlide [Stepper Motor Digital Reference] Focuser M5A (see FOCUSERS link, AUTOFOCUS link for electronic hardware package), includes Quad-Focus (micro, mini, median & macro), Robo-Focus stepper motor and hardware mounted on M5. Purchase stepper motor interface hardware and software separately.
Both above motor packages for MasterGlide Focuser M5B (see FOCUSERS link, AUTOFOCUS link for electronic hardware package), includes Quad-Focus (micro, mini, median & macro), VSI [interchangeable] motor mounting hardware installed on Robo-Focus stepper motor and DC servo motor with Dual-Control hand paddle and 120vac wall-wart power supply (optional 12vdc car lighter adapter).

*M5s have an extra 3/4" profile to accommodate the clearance needed for the digital read-out.

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2" MicroGlide QUICK REFERENCE Guide

2" MicroGlide Epsilon Focuser MGF1
2" MicroGlide Epsilon Focuser MGF1 (motorized autofocus capable). An ultra-sensitive 2" secondary focuser for SCTs with existing primary focus. A patented Van Slyke Drive mechanism moves the tube in and out like no other focusing mechanism before it. The MicroGlides offer ultra-smooth and tactile-sensitive [micrometer head] control for micro-focusing applications. No other focuser on Planet Earth provides this type of unparalleled and sophisticated focusing operation. Optional autofocus control offers the finest step-to-tube movement ratio available. More than a factor of 10 better than any other focuser on the market (one motor step = 0.0000069" of actual tube travel). Order optional Docking Adapters as described below.
Docking Adapters, required to dock Epsilon focuser to your scope. Optional docking adapters are available for all popular scopes on the market. They are listed at the DOCKING ADAPTERS link above right. If you don't find your specific docking adapter, call VSI and we'll custom machine one for you. Interchangeable docking adapters provide the use of multiple scopes utilizing one Epsilon focuser. Select your DOCKING ADAPTERS from bottom of this web page
Robo-Focus stepper motor, required to autofocus [computer control] your MicroGlide focuser. You must order the electronics hardware package from Technical Innovations (TI). See AUTOFOCUS link above right for more info and direct link to TI. All Robo-Focus gear reduced stepper motor control offers temperature compensation. TI stepper motor includes wired and mounted DB9 plug. Order Item RFM: $99
Mounting hardware kit (not shown), required to mount the above Robo-Focus motor to the MicroGlide focuser. This mounting hardware kit and motor are pre-installed on your MicroGlide focuser when you place your order for the motor and mounting kit, all at the same time. Order Item MTH1: $89

2" MicroGlide Omicron Focuser MGF2
2" MicroGlide Omicron Focuser MGF2 (motorized autofocus capable). An ultra-sensitive 2" primary focuser for refractors, etc. without existing primary focus. A patented Van Slyke Drive mechanism moves the tube in and out like no other focusing mechanism before it. The MicroGlides offer ultra-smooth and tactile-sensitive [micrometer head] control for micro-focusing applications. No other focuser on Planet Earth provides this type of unparalleled and sophisticated focusing operation. Optional autofocus control offers the finest step-to-tube movement ratio available. More than a factor of 10 better than any other focuser on the market (one motor step = 0.0000069" of actual tube travel).
Docking Adapters, required to dock Omicron focuser to your scope. Optional docking adapters are available for all popular scopes on the market. They are listed at the DOCKING ADAPTERS link above right. If you don't find your specific docking adapter, call VSI and we'll custom machine one for you. Interchangeable docking adapters provide the use of multiple scopes utilizing one Omicron focuser. Pictured at right is a representation of what you receive when you purchase a specific docking adapter for your telescope. Select MicroGlide ADAPTERS from the navigation at the top of this page or scroll to the bottom.
Drawtubes (2.25"OD x 2"ID), required for Omicron focuser. Optional drawtubes are available in 2" and 6" lengths, one for SCTs and one for non-SCTs. In other words,  the short 2" drawtube can be used on SCTs, however the EPSILON is recommended because you don't need a drawtube on an SCT with primary focus. The non-SCT 6" long drawtube is used when you want to dock an Omicron to [say] a refractor as a primary focuser, etc. There is also a special threaded drawtube specifically for the SBIG STL11000 CCD camera that replaces the standard drawtubes. This application provides the necessary 2" internal clear aperture reguired for the STL's large chip. Different length drawtubes can be custom machined. Select your DRAWTUBES at the bottom of this web page
Robo-Focus stepper motor, required if you want to autofocus [computer control] your MicroGlide focuser. You must order the electronics hardware package from Technical Innovations (TI). See AUTOFOCUS link above right for more info and direct link to TI. All Robo-Focus gear reduced stepper motor control offers temperature compensation. TI stepper motor includes wired and mounted DB9 plug. Order Item RFM: $99
Mounting hardware kit (not shown), required if you want to mount the above Robo-Focus motor to the MicroGlide focuser. This mounting hardware kit and motor are pre-installed on the MicroGlide focuser when you order the focuser, motor and mounting kit at the same time. Order Item MTH1: $89

2" MicroGlide Coupling Focusers MGFCOs
2" MicroGlide Coupling Focusers MGFCOs (not shown) Same specs as MGF1 and MGF2 above. For more detailed info and pictures, click on 2" MicroGlide MORE at the top of this web page, then scroll down to the section "About the MicroGlide [in-line] COUPLING Focusers."

*IMPORTANT NOTES follow:

MGF1 Epsilon focusers are designed to be SECONDARY focusers, and do not require drawtubes, but do require a docking adapter. They do not include built-in drawtube capability and have standard 2" ID moving tubes that accept your 2" format barrel nose eyepieces and accessories.

MGF2 Omicron focusers are designed to be PRIMARY focusers . They require optional moving tubes, with a 2.25" inside diameter, that do not accept your standard 2" format eyepieces and accessories, and require the use of our optional 2" format drawtubes, offered separately at the DRAWTUBES link. This functional design offers near-zero profile, full drawtube insertion into the Omicron's moving tube. This unique drawtube option provides your Omicron with more back focus range (up to 12" with custom drawtube) than any other commercial focuser available today, while also providing a selective choice of back focus travel, depending on which drawtube you choose. Drawtubes, Docking Rings & Spinners sold separately.

MGFCOs are designed to be 2" format COUPLING focusers mainly for hi-end APO refractors, and need no other drawtube, docking adapter or accessory to operate. Depending on which model you choose, your co-focuser will have built-in male and female threads for an AstroPhysics, Takahashi or Meade refractor. They are not interchangeable between the three scope thread formats and are dedicated to the scope format you choose. They have an oversize 2.25" clear aperture, so the largest CCD chips will not be vignetted by passage of your scope's light cone through the co-focuser to get to your CCD camera. The major advantage is to add autofocus capability to your scope without fussing around with "Mickey Mouse" modifications to your existing scope's focuser via aftermarket universal mounting kits that really don't properly fit any scope.

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3" MacroGlide ALPHA/OMEGA Docking Focusers

Manual, DC Servo (analog) & Auto-Focus Stepper (digital) Motor Control

Without Comparison, the Finest Feature-Packed Focusers on Planet Earth

If you're THINKING "larger than 2 inch" FOCUSER, THINK GLIDERS for the FOLLOWING REASONS

Mount any VSI Focuser to any Scope - Not just Meade & Celestron

AP, Borg, OGS, RC Optical, Takahashi, TeleVue, TMB, Vixen, etc., etc. - Just Call VSI

MACROGLIDE Features & Specifications:

Introducing VSI's GIGANTIC 3" MacroGlide ALPHA/OMEGA Docking Focusers. The huge dual 3" diameter custom machined knobs and smaller dual micro-focus knobs (5 to 1 ratio reduction), now copied by many, have made a comeback on this mega-focuser. These giant 3" focusers conform to the existing 2.7" SAE and 72mm (2.835") metric threaded standards set by these established formats. Our focuser's moving tube, TRUE internal clear aperture is a full 3 inches. In fact, our proprietary output adapter format diameter is 3.1 inches (see Output Adapters link above right). This massive focuser is available for refractors (ALPHA model) with a whooping 5" of tube travel (primary focuser), and SCTs (OMEGA model) offering 1" of tube travel (secondary focuser). Custom tube travel lengths are available by special order.

MacroGlide focusers can couple directly to our Zerotators, Sidewinders, or Targetrons using the same 2.9" flanged format, so port rings are 100% interchangeable. You can stack components (see picture at left) in any configuration you want using coupling port rings (see Output Adapters link above right, and Sidewinder Docking Port Rings link) that only consume 1/8" of profile. Add a [1-inch profile] Zerotator (see Rotators link) to your MacroGlide and gain rock-solid, zero-flexure, super-fluid, radial ball-bearing Z-axis rotation of your entire imaging train. And our ATLAS Zerotator can handle any load you throw at it - guaranteed!

Each of the ALPHA/OMEGA focuser models have been optimized, for their specific function, from the ground up. The OMEGA has been designed with the shortest profile possible (2.75") as a secondary focuser for SCTs, etc. In fact, it's the same profile as the 2" MasterGlide M1 through M3 focusers, but much "fatter." The ALPHA model was designed for maximum rigidity as a primary focuser for refractors, etc. It has a slightly longer minimum profile (3.5") due to extended spacing between the massive Crayford bearings, and extra metal between those bearings, that are mounted on the focuser housing. This design creates a stronger, more rigid moving tube to better support the ALPHA's 5" of tube travel.

As you can see by the 3" diameter knobs, the OMEGA SCT model has only 2.75" of profile (same as our 2" MasterGlide focusers M1 through M3). Of course, DC servo (w/hand paddle) and/or autofocus stepper motor control are available (purchase stepper motor electronic hardware package from Technical Innovations, $295, see Autofocus link for more info). Interchangeable docking and output rings (optional) are available for every telescope and application possible.

Over the years VSI has continually taken the best features of all our previous focuser designs and incorporated them into new "super focuser" models. We do this not only to continually improve our products, but to [also] leave copy-cats in the dust. Of course, these VSI knock-offs are the greatest form of compliment!  It tells you that VSI products are always the best by design, function and application. The only way to keep ahead of these imitators is to design new and creative focusers faster than they can copy our designs and incorporate them into their product lines. This unique design philosophy has pioneered our Crayford focuser development since John Wall first invented it back in the early 1970's (see "Brief History of the Crayford Focuser" below), and kept VSI on the "cutting-edge" of focuser design for decades.

What we consider to be the most important mechanical feature is the dual pressure points on the Crayford rod. Instead of one pressure point, which has now been copied by just about every focuser manufacturer around, VSI now uses two identical Teflon pads with two large set screws (see picture right). This design upgrade literally doubles the pressure applied to the Crayford shaft, in effect doubling the holding power. By applying equal pressure along a full 1-inch length of the Crayford rod and the entire 1-inch width of the moving tube's machined flat, you create a more positive rack & pinion-like movement, while cutting your tactile contact, necessary to move the focusing tube, in half. In other words, all our Gliders have super-smooth, true feather action control. This creates an incredibly soft-touch, tactile manual focusing function that no other focuser can begin to offer.

Our QUAD-LOCK system is incorporated in our 2" reducer output port insert ring  (item #A312R pictured right) offering astroimagers a rock-solid coupling between a MacroGlide focuser's moving tube and your 2" barrel nose. Four tightening screws lock your 2" barrel nose into the focuser's moving tube - two 10-32 Nylon thumb screws and two [hidden] 8-32 set screws. The first two thumb screws, opposed by 90 degrees, lock your barrel in place from one end of the tube, and the other two set screws lock from the other end of the tube. This 4-screw application allows any 2" barrel nose to meld with the MacroGlide focuser's moving tube, creating a zero-flexure coupling. See VP Accessories link for more info on VSI's exclusive adapters.

VSI's massive 3" focusers are designed for astroimaging. So creating a rock-solid coupling between the focuser's moving tube and your extended imaging train is mandatory. As you know, 2" and 1.25" barrel nose formats are the "weak link" between your focuser and long extended imaging trains. These barrel nose formats are for eyepieces but, somehow, all standard focusers have always been created to accept this [less than adequate] format - even VSI focusers. Very seldom do you insert an eyepiece directly into a focuser, unless you are using a Newt/Dob for visual observing. You [at least] have a standard diagonal between your focuser and eyepiece, when using catadioptric and refractor type scopes. Now you can convert a MacroGlide focuser's standard 2" barrel-nose insert reducer (Item #A312R) to solid, low-profile [industry-standard] threaded formats (2"-24tpi threads, or standard 42mm-0.75mm thread pitch T-thread) with the simple use of VSI adapters (item #A2LT & #AT2, see links). And the coupling is [now] rock-solid so you can stack an extended, long profile imaging train onto these threaded couplings without flexure!

These two hidden [captive retaining] set screws on the MacroGlide focuser's insert adapter (pictured right) are also designed to hold our Hexagonal 1 or 2 in the focuser. A specially grooved barrel nose on the Hexagonal (see Hexagonal link for details) allows you to freely rotate the active eyepiece position to obtain a more comfortable viewing position. This [dual-purpose] QUAD-LOCK system is a VSI exclusive, not found on any other focuser.

To further reduce noise and vibration, and better isolate the focusing motor(s) from the focuser housing, the motor's drive shaft is [now] coupled to the Crayford focusing shaft using precision Delrin spur gears. VSI is switching from metal to Delrin spur gears because Delrin (an indestructable polymer resin) is more durable and lasts longer. And, VSI uses only the best Delrin gears available, with double metal set screws that lock the spur gears securely to the motor and Crayford drive shafts.

MacroGliders are extremely massive in design and size compared to all other focusers on the market. The single pictures at this web site can't impress the “giant” proportions of these huge, rock-solid focusers (outer housing dia. = 4.25”). To illustrate this proportional difference, a Commercial 2" focuser Size/Mass Comparison was created below.

VSI focusers utilize the famous "Crayford" design, which is world renown for its zero-image-shift, zero-backlash and simple mechanical qualities. Unlike the other "Crayfords" on the market, that use a cylinder section to hold their four bearings in place (they also claim being first to do so, but this Crayford redesign was originally introduced by Paul Van Slyke and copied by others, see S&T Feb 1986, P199 or go to "Four-Speed 17.5" Newt" link for article re-print), the Glider's housing is a complete cylinder with four 1" diameter [Crayford] ball bearing secured to the housing on both sides of all the bearings (patented), providing a much higher degree of stability and load handling capability. Instead of using two bearings [supported by a frame] at each end of the Crayford drive shaft to provide pressure on the moving tube, VSI's Crayford design uses a dual pressure point on the rotating drive shaft (supported with two pure virgin Teflon pads), which offers a fluid surface so near-infinite force can be applied with no possible warpage of the drive shaft (also copied by others). Previously, commercially available Crayford-style focusers offered a flimsy, flexure-ridden housing with [what I call] "slip & slide" focusing. These other focusers are adequate for casual sky observing with eyepieces, but critical astroimaging with heavier, leveraged imaging trains was impossible. No positive focusing action, like with R&P focusers, could be achieved - until now. The Glider movement is not only as smooth as a 20 year-old, single-malt Scotch whiskey, but the silky action is extremely positive and reactive to the slightest touch, especially with those GIANT 3" diameter focusing knobs.

Another exclusive VSI feature is the vibration dampening system. Note the brass motor bracket arm (see pictures). Brass, having a very high density, is the best material to dampen motor vibrations when a motor must be in close proximity to the eyepiece, like focusing motors. This undesirable vibration can easily transfer to what you see in your telescope's eyepiece.

WARNING: Be aware that all [so-called] Crayford focusers, are not really Crayford focusers. Deceptive advertising by many dealers, trying to take advantage of the Crayford's reputation, offer Crayford-type, Crayford-like or Crayford-style focusers that have very little to do with the true Crayford design. NO radial ball bearings, NO zero-image-shift, NO fluid motion, NO ultra-tactile sensitive control, NONE of the above functions that made the Crayford the finest precision focuser on Planet Earth. These non-Crayford focusers typically use plastic pads to simulate Crayford bearings and other inferior construction techniques that deminish the Crayford name. Only a focuser that uses four (or five, like VSI's MicroGlider) precision ground steel, radial ball bearings can [rightfully] be called a Crayford focuser. - PVS

VSI's NEW Coma Corrector Insert Capability

Our MacroGlide ALPHA focusers can now accept all 3" outside diameter coma correctors on the market, including Astro Optik's Newton-Wynne 3" Coma Corrector (made in Germany), pictured at right. All ALPHA moving tubes have a 3.005" internal diameter to easily accept the insertion of these unique coma correctors. Pictured at right (left image) is a standard 3" coma corrector with an optional T-thread adapter bolted to the top that provides the exact 60mm distance between the corrector lens and your CCD chip. This one accepts any CCD camera that has a standard T-thread coupling, like the SBIG ST10 CCD camera (shown). Just screw the camera onto the coma corrector adapter (center image) and insert it in the MacroGlide ALPHA focuser (right image) and tighten the three thumb (or set) screws opposed by 120 degrees. You can also use the 6" long coma corrector's barrel as a push/pull drawtube, if desired. When not using the coma corrector, just remove it and drop in our standard output adapters. VSI's output adapters include 2" barrel-nose, T-thread, 2"-24tpi thread, and SBIG's new 2.156"-24tpi thread for their STL11000 CCD camera (see OUTPUT ADAPTERS link above).  Of course, custom machined output adapters are always available. Although our ALPHA's have a long 5" travel, shorter custom moving tube lengths/travels are also available by special order.

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2" MasterGlide Docking Focusers

Manual, DC Servo (analog) & Auto-Focus Stepper (digital) Motor Control

Without Comparison, the Finest Feature-Packed Focusers on Planet Earth

If you're THINKING  about a FOCUSER, THINK GLIDERS for the FOLLOWING REASONS

Mount any VSI Focuser to any Scope - Not just Meade & Celestron

AP, Borg, DFM, OGS, RC Optical, Takahashi, TeleVue, TMB, Vixen, etc., etc. - Just Call VSI

NEWER MASTERGLIDE Features:

Standard MASTERGLIDE Features & Specifications:

VSI's [2" format] MasterGlide Focuser has so many NEW features that it also demanded a new name to commemorate this completely redesigned super stable, ultra-high performance, secondary SCT focuser. Over the years VSI has continually taken the best features of all our previous focuser designs and incorporated them into new "super focuser" models. We do this not only to continually improve our products, but to [also] leave copy-cats in the dust. Of course, these VSI knock-offs are the greatest form of compliment!  It tells you that VSI products are always the best by design, function and application. The only way to keep ahead of these imitators is to design new and creative focusers faster than they can copy our designs and incorporate them into their product lines. This unique design philosophy has pioneered our Crayford focuser development since John Wall first invented it back in the early 1970's (see "Brief History of the Crayford Focuser" below), and kept VSI on the "cutting-edge" of focuser design for decades.

What we consider to be the most important new mechanical feature is the dual pressure points on the Crayford rod. Instead of one pressure point, which has now been copied by just about every focuser manufacturer around, VSI now uses two identical Teflon pads with two large set screws (pictured right). This design upgrade literally doubles the pressure applied to the Crayford shaft, in effect doubling the holding power. By applying equal pressure along a full 1-inch length of the Crayford rod and the entire 1-inch width of the moving tube's machined flat, you create a more positive rack & pinion-like movement, while cutting your tactile contact, necessary to move the focusing tube, in half. In other words, our Gliders now have super-smooth, true feather action control. Couple this feature with our new Spinners (see paragraph below) and you've created an incredibly soft-touch, tactile manual focusing function that no other focuser can begin to offer.

Probably the second most important feature is our new 4-inch diameter Spinner knobs (pictured left). The Spinner arms are 1/4" diameter aluminum rods that protrude from the basic cylindrical knob every 60 degrees. With six Spinner rods to manipulate your focus position, you'll always have at least one or two in a comfortable position. Spinners not only increase your resolution by a factor of 4, they also provide 4 times the touch torque, making it that much easier to manipulate your focusing position manually. Ease of movement and feather action control doesn't get any better. I've found from experience that placing one spinner rod between two fingers allows for super sensitive, fine focusing control of your moving tube's position. Of course, not as fine as our exclusive Manual Micro-focus Tangent Arm. And for major changes in focus position, just spin the Spinner with one finger, it doesn't get any quicker! Spinners are also offered separately for your older model VSI Focuser or any aftermarket focuser with 1/4" diameter shafts.

Another exclusive and unique feature is our new internal [moving tube] locking splines (pictured right). Every Glider moving tube now has 200 locking splines cut into their moving tube's inner wall. This machined splining operation provides a super gripping action with minimal applied thumb screw pressure. The holding action is comparable to a complicated, and difficult to machine, compression locking mechanism, but is much faster and easier to release when you need to rotate your imaging train to find that evasive guide star, etc.

Other NEW features include: 1) a repositioned moving tube locking thumb screw. When positioned conventionally [before], it allowed the Crayford moving tube to be cocked to the side when too much pressure was applied. Now, with central positioning between and opposed to our massive Crayford bearings, you can apply unlimited pressure to ensure a secure moving tube lock down; 2) weight reduction machining that doesn't impede the structural integrity of the focuser; 3) new ultra-precision digital turning and milling techniques that provide consistent perfect part mating every time.

Our NEW QUAD-LOCK system (pictured at right with the focuser extended to expose the two additional locking set screws) offers astroimagers a rock-solid coupling between a MasterGlide focuser's moving tube and your 2" barrel nose. Four tightening screws lock your 2" barrel nose into the focuser's moving tube - two 10-32 Nylon thumb screws and two [hidden] 8-32 set screws. The first two thumb screws, opposed by 90 degrees, lock your barrel in place from one end of the tube, and the other two set screws lock from the other end of the tube. This 4-screw application allows any 2" barrel nose to meld with the MasterGlide focuser's moving tube, creating a zero-flexure coupling. See VP Accessories link for more info on VSI's exclusive adapters.

VSI's massive 2" focusers are designed for astroimaging. So creating a rock-solid coupling between the focuser's moving tube and your extended imaging train is mandatory. As you know, 2" and 1.25" barrel nose formats are the "weak link" between your focuser and long extended imaging trains. These barrel nose formats are for eyepieces but, somehow, all standard focusers have always been created to accept this [less than adequate] format - even VSI focusers. Very seldom do you insert an eyepiece directly into a focuser, unless you are using a Newt/Dob for visual observing. You [at least] have a standard diagonal between your focuser and eyepiece, when using catadioptric and refractor type scopes. Now you can convert a MasterGlide focuser's standard 2" barrel nose format to solid, low-profile [industry-standard] threaded formats (2"-24tpi threads, or standard 42mm-0.75mm thread pitch T-thread) with the simple use of VSI adapters (item #A2LT & #AT2 shown at right). And the coupling is [now] rock-solid so you can stack an extended, long profile imaging train onto these threaded couplings without flexure!

These two hidden [captive retaining] set screws on the MasterGlide focuser's moving tube (pictured right) are also designed to hold our Hexagonal 1 or 2 in the focuser. A specially grooved barrel nose on the Hexagonal (see Hexagonal link for details) allows you to freely rotate the active eyepiece position to obtain a more comfortable viewing position. This NEW [dual-purpose] QUAD-LOCK system is a VSI exclusive, not found on any other focuser.

To further reduce noise and vibration, and better isolate the focusing motor(s) from the focuser housing, the motor's drive shaft is [now] coupled to the Crayford focusing shaft using precision Delrin spur gears. VSI is switching from metal to Delrin spur gears because Delrin (an indestructable polymer resin) is more durable and lasts longer. And, VSI uses only the best Delrin gears available, with brass insert hubs and double metal set screws that lock the spur gears securely to the motor and Crayford drive shafts.

The Glider's other standard features include an outer housing that docks and locks to the rear of your SCT's visual back utilizing the larger 3.25"-16tpi threaded format for Meade, and an adapter ring (#AMC33, $99) for Celestron 3.29"-16tpi visual backs. This very important large format docking totally eliminates flexure with even long, extended imaging trains. Unscrew your 3.25" to 2" Meade or Celestron Reducer on your SCT's visual back and take a close look at it. Do you really think that this thin, flimsy reducer can hold your imaging train without flexure. VSI won't even offer a focuser that attaches to this 2"-24tpi [wimp] reducer for this reason. Why do you think people like Dr. Frank Melsheimer of DFM, or John Stiles of OGS are so emphatic about massive visual back assemblies, etc. Because without a solid visual back, your pointing and tracking accuracy simply goes away. This flexure is mainly due to the effects of gravity on your scope as your pointing position changes over time. No matter how well a secondary focuser is built, if it is attached to this flimsy 3.25" to 2" reducer, it will induce unacceptable flexure into your imaging train, period. NOTE: John Stiles insisted that my custom machined mounting plate (to dock a customer requested MasterGlide focuser) on one of his 20" OGS Cassegrains was at least 12" in diameter and 1/2" thick minimum (see User Installations link, Leeward Community College). Gliders are extremely massive in design and size compared to all other 2” format focusers on the market. The single pictures at this web site can't impress the “giant” proportions of these huge, rock-solid focusers (outer housing dia. = 3.5”). To illustrate this proportional difference, a Commercial 2" focuser Size/Mass Comparison was created below.

The perfect marriage (if there is such a thing) between focuser and rotator! Combining our manual Zerotator and MasterGlide focuser (pictured at right) creates a rock-solid, stable rotating platform for astroimaging or just rotating your diagonal or Hexagonal to a more comfortable viewing position. The radial ball bearing loaded Zerotator can handle any load you stack on it, because it was designed to hold your entire imaging train - focuser, optical manifold, CCD camera, etc., etc. And it has a 2.75" internal clear aperture so vignetting is not a problem.

VSI focusers utilize the famous "Crayford" design, which is world renown for its zero-image-shift, zero-backlash and simple mechanical qualities. Unlike the other "Crayfords" on the market, that use a cylinder section to hold their four bearings in place (they also claim being first to do so, but this Crayford redesign was originally introduced by Paul Van Slyke and copied by others, see S&T Feb 1986, P199 or go to "Four-Speed 17.5" Newt" link for article re-print), the Glider's housing is a complete cylinder with four 1" diameter [Crayford] ball bearing secured to the housing on both sides of all the bearings (patented), providing a much higher degree of stability and load handling capability. Instead of using two bearings [supported by a frame] at each end of the Crayford drive shaft to provide pressure on the moving tube, VSI's Crayford design uses a single center pressure point on the rotating drive shaft (supported with a pure virgin Teflon pad), which offers a fluid surface so near-infinite force can be applied with no possible warpage of the drive shaft (also copied by others). Previously, commercially available Crayford-style focusers offered a flimsy, flexure-ridden housing with [what I call] "slip & slide" focusing. These other focusers are adequate for casual sky observing with eyepieces, but critical astroimaging with heavier, leveraged imaging trains was impossible. No positive focusing action, like with R&P focusers, could be achieved - until now. The Glider movement is not only as smooth as a 20 year-old, single-malt Scotch whiskey, but the silky action is extremely positive and reactive to the slightest touch.

The VSI MasterGlide Focuser is designed for the current generation of Meade/Celestron Schmidt-Cassegrain telescopes (10" and larger) that focus by moving their primary mirrors (which always have an unacceptable amount of lateral image shift when focusing), and accept accessories via their standardized threaded visual backs. However, Gliders can also be used with any other type of telescope using optional VSI screw-on or custom docking adapters. Since the Gliders are specifically intended  to be secondary docking focusers, and work in conjunction with scopes that have wide-range primary focusing mechanisms, the travel range is kept relatively short (around 1"), but more than adequate for any focusing application. The Glider's shorter focus travel is actually many times the amount required to adjust and pin-point focus your SCT, because your primary focuser's large focusing range can easily place the image at a "ballpark" point between the secondary docking focuser's lesser range. 

The blow-up picture at right illustrates the Glider's [ultra] micro focusing mechanism. This manual micro focusing tangent arm is [by more than a factor of 10] finer than any other focuser on the market (1 full turn of the Glider's micro focusing knob equals an incredible 5/1000" of tube travel). Even the dual coarse/fine control knob ones can't even come close to those specs. It is specifically designed for astroimaging focus control applications - not manual visual focusing. In fact, it's the only focuser control, I know of, that is fine enough to provide dead-on manual focus in conjunction with a computer/CCD focusing subroutine. This manual micro-focusing feature provides a 10 turn maximum range that equals a micro-travel range of 0.05 inches The bottom [slotted head] knob locks in the micro-control tangent arm at any point along the focuser's tube travel range. Then just turn the top larger knob (10 turn maximum range) for focusing so fine that you would have extreme difficulty seeing the focusing tube move even with a full revolution of the micro-focusing knob. Can you see a movement of 0.005 inches?

Another exclusive VSI feature is the vibration dampening system. Note the brass arms (see pictures at model links) on the manual micro-focus control arm and [most important] the motor bracket arm. Brass, having a very high density, is the best material to dampen motor vibrations when a motor must be in close proximity to the eyepiece, like focusing motors. This undesirable vibration can easily transfer to what you see in your telescope's eyepiece.

The VSI Crayford docking focuser's analog and digital readouts (see M4 & M5 links) indicates focus position directly from the moving tube for accurate, repeatable positioning every time. Others indicate position from the Crayford's [slip & slide] focusing shaft providing a totally useless, decorative "bauble" that serves no purpose whatsoever. VSI's analog [M4] dial indicator has a rotating outer bezel with lock, two adjustable set mark indicators, increments of 0.001 inches (with interpolation to better than 0.0001"), and a smaller rotation dial that indicates a full inch of travel. VSI's digital [M5] read-out has inch/mm selection, zero and origin buttons with a digital numerical resolution of 0.0005" or 0.01mm. This model incorporates the same high quality Mitutoyo digital readout that was installed on our discontinued Monster and Super Power Focusers. You can also purchase an optional remote position display box (pictured below under M5 Options) that just plugs into the side of the local LCD digital readout on the M5 itself.

VSI MasterGlide docking focusers are available in five base models, with various motorized features available within each M3, M4 or M5 model (A, B, etc.) which are all pictured at their respective links above right: M1, basic [no-frills] with no options; M2, includes manual Tri-Focus control [only]; M3 includes manual Tri-Focus control and remote motorized control, hand paddle and power supply; M4 is a fully loaded unit with all of the above features plus Quad-Focus and analog readout; M5 is a fully loaded unit with all the above features plus Quad-Focus and digital readout. M1 through 3 have a 2.5" profile, where the M4 & 5 have a 3.25" profile to accommodate the analog/digital readout mechanisms. Glider docking bases are threaded (3.25"-16tpi, Meade format) to easily screw directly onto the visual backs of any 10" or larger Meade SCT except 16" Meade LX200, which requires a special ring converter (item #ACR43) offered at the Docking Converters link. For Celestron installation (3.29"-16tpi, C11 or C14), you need our Meade to Celestron converter ring (item #ACM33) offered at the Docking Converters link. VSI MasterGlide focusers will NOT dock with 8" SCTs because of their smaller 2" threaded visual backs (see MicroGlide focusers link). Custom machined docking mounts are available for your refractor or any other type of telescope. Nylon thumb screws, located at the base of the Glider housing, lock down the focuser [against your visual back's threads] in any rotational position relative to your scope's visual back.

WARNING: Be aware that all [so-called] Crayford focusers, are not really Crayford focusers. Deceptive advertising by many dealers, trying to take advantage of the Crayford's reputation, offer Crayford-type, Crayford-like or Crayford-style focusers that have very little to do with the true Crayford design. NO radial ball bearings, NO zero-image-shift, NO fluid motion, NO ultra-tactile sensitive control, NONE of the above functions that made the Crayford the finest precision focuser on Planet Earth. These non-Crayford focusers typically use plastic pads to simulate Crayford bearings and other inferior construction techniques that deminish the Crayford name. Only a focuser that uses four (or five, like VSI's MicroGlider) precision ground steel, radial ball bearings can [rightfully] be called a Crayford focuser. - PVS

Focal Reducer "HIDDEN CAVITY" Super Feature

All models of MasterGlide Docking Focusers have our exclusive Focal Reducer "Hidden Cavity" feature machined into the rear of their moving tubes. Just insert your Celestron or Meade focal reducer into the rear of your Glider, and your new, focal reduced profile has just been cut to zero. Then reinstall your MasterGlide focuser, insert a standard 2" diagonal or VP Slider in your [focal reducer equipped] Glider and you're ready for super stable, efficient, low-profile, wide-field operation.

You can also use this focal reduced configuration in your MasterGlide focuser mounted on other [similar focal length] scopes, not just commercial Celestron/Meade Schmidt-Cassegrains. Even if you don't use a focal reducer in your focuser's hidden cavity, the larger internal diameter provides an ultra-wide clear aperture that guarantees no vignetting, even with very fast scopes. Note that the internals of the above focuser were intentionally NOT flat blackened for demo purposes only.

This unique "hidden cavity" super feature has been around since the beginning of VSI. Over two decades. You may remember the old Monster focusers, now called MasterGlide. I changed the name because everyone and their brother was calling everything "monster this" and "monster that," etc. In fact, they still do. Maybe you remember my old "monster" display ads in S&T, with the picture of a monster coming out of my focusers that was a cross between "The Creature from the Black Lagoon" and a T-Rex? If you are at all familiar with VSI, then you know that I like to "march to a different drum." Honor, reputation and dignity are business and marketing traits that are unfamiliar to most.

Speaking of that, a relatively new focuser business, who seems to be filtching more than just my ideas from others, has "borrowed" my design and now features it in a small display ad in S&T's Market Place. Am I ever bothered by these unethical copycat activities? No, because it is the grandest form of flattery. A compliment that has no comparison. And it is not even a true Crayford focuser, so that makes the theft even more meaningless. As I have mentioned before, Crayford-type, Crayford-style and Crayford-like do not make a true [radial ball bearing] Crayford focuser, and VSI's bearings are five times the size of anyone elses. It is an insult to John Wall, the inventor of the Crayford focuser (see bottom of this web page), to use the "Crayford" name to describe a pseudo-Crayford knock-off at best. Besides, my unique products are never based on one or two features, like others. As with all my products, they are bases on an overall design concept that is timeless - a build-quality that will endure far beyond your lifetime.

Although I do have a couple of patents, this is not one of them. So rampant pilfering of many of my design features, including this one, is an on-going activity. Over the years I have found that patents are not worth the initial expense (i.e attorney's fees, patent fees, maintenance fees for the life of the patent, etc.). And you can literally go broke fighting patent infringements through the courts.

VSI's Exclusive Zenith Lift System

VSI's Zenith Lift System (patented), installed on all MasterGlide focusers, provides a unique lift feature that balances focus control at the zenith, or near zenith, observing/imaging positions. The Zenith Lift System (ZLS) was created so the astroimager, or visual observer, can easily take advantage of the more transparent overhead zenith arena. If balanced zenith lift is not needed, you can easily remove the springs by slipping the hooked ends over the Allen screws - instant gone!

FYI, this Zenith Lift System has nothing to do with backlash, as others have wrongly assumed in their display ads. They are trying to discredit the ZLS without even understanding its function. The more they try (desperately) to "poo-poo" VSI products, the more they humiliate and embarrass themselves. When will they learn that you can't destroy the reputation of a good product with words, especially words that only reveal their own jealousy and ignorance. A product can only destroy itself by its own actions. - PVS

We all know that you are looking through about 100 miles of atmospheric distortions on your horizon, but you are only observing through about 10 miles of atmosphere at your zenith. Obviously, you will obtain the best astroimages and visual observations when your scope is pointing straight up.

The mechanical apparatus comprises two heavy-lift springs (one is pictured at right) that are attached between the focuser housing and the moving tube on both sides of the focuser. Also, the Glider's mechanical spring-loaded lift system will greatly assist your autofocus stepper motor and DC servo motor when working around the zenith.

HINT: By setting your focus point further in, or further out, you vary the amount of lift capability to better balance your focuser's load. In other words, rack your focuser in most of the way, and you have light lift for a lighter load. Rack your focuser out most of the way and you have heavy lift for extended imaging trains. Just set your SCT's primary focus at the inner, or outer, point of your secondary focuser travel for different loads. Of course, if your load is light, and your're observing near the horizon (say, in your neighbor's window) you don't need the mechanical lift springs. Simply slip the springs over the Allen head screws to remove them.

How does Tri-Focus & Quad-Focus Operate?

Why design all these redundant focusing controls into a focuser? Because we can, and to push the engineering envelope to a point where no one else would dare venture. But most of all, we do it for you, because we know that many of our clients love functional gadgetry as much as we do. Knobs, gadgets and gages are very "fresh" (aka cool). Others would also call it gaudy. We simply call it open-frame, functional versatility worthy of an Arlen Ness, Jesse James or Indian Larry (now deceased) chopper. However, you do have to be marginally driven to develop a focuser with FOUR different manual focusing controls. That's four different knobs that offer manual speed ranges from a moderately fine main focusing ratio (compared to other focusers on the market) to a micro-focusing tangent arm [for astroimaging] where one revolution of the control knob equals less than 0.005" of tube movement - Whoa!

Since VSI is the only one who has ever offered this extreme range of multi-focusing control, an in-depth explanation of these unique manual/knob controls is necessary. Of course, once you receive your MasterGlide focuser, operation of the various focusing controls is a no-brainer - just turn the knobs and enjoy the feature-packed, super-sensitive and smooth focusing capability no other focuser on Planet Earth has ever offered, or probably ever will.

On to the operation of the four levels of manual focus control, two of which are new. The main macro-focusing Spinner knob (see MACRO above left), with its six evenly spaced spoke-arms, is unique to itself and offers 4 times the tactile sensitivity of a conventional focusing knob, and directly rotates the hardened-steel 1/4-inch diameter Crayford shaft. This specially machined Crayford shaft is actually turned down to a central diameter of 0.15" where it contacts the moving tube's flat. This additional diameter reduction gives all MasterGlide focusers a much finer "coarse" focusing compared to other focusers.

The first gear-reduction (MEDIAN) is through a pair of Delrin spur gears with a reduction of 3 to 1, noted above left (REDUCTION 1). This moderate reduction is then transferred to the left side of the focuser through a second 1/4" diameter hardened-steel drive shaft, mounted directly below the primary Crayford shaft, where it terminates into a small aluminum knob (MEDIAN, shown above) on the Quad-Focus M4 and M5, and a large aluminum knob on the Tri-Focus M2 and M3. This intermediate reduction will probably not be used much on M4 and M5 focusers (see picture of Quad-Focus M5 below right) that have the further reduced mini-focus (crank-knob) directly attached, but decoupled from the main Crayford drive shaft, or [what we call] Quad-Focus, but it will be very useful on the M2s and M3s (see picture of Tri-Focus M3 below left). This [left-over] redundant median-focus control could have been removed in M4/M5 production, but since it was easier to keep, and ergonomically placed in relation to the further reduced mini-focus crank-knob, we decided to leave it in place for the time being, or until our valued clients tell us they don't like it, or they think it gets in the way of other functions, etc.

The second gear-reduction (MINI, aka crank-knob) is delivered through a second set of identical-ratio (3 to 1) Delrin spur gears to a third crank-handle knob that is the same size as the Spinner knob (without the six spokes) and resides on the opposite end of the main Crayford shaft. It spins freely on the left side of the main Crayford drive shaft, held in place by a lateral keyway, and is driven by a final 3 to 1 spur gear reduction. It rotates so easily that a crank handle was installed on the knob (like our MicroGlide focusers) to facilitate a choice of hand-rotation from the same knob. Since this control knob is directly installed on the opposite end of the main Crayford control shaft, it offers perfect ergonomic operation. In other words, turn the main focusing knob on the right side (Spinner knob) and you are provided with direct Crayford shaft rotation (1 to 1). Turn the focusing knob on the left side of the same Crayford shaft (crank knob) and you are provided with a 6 to 1 reduction. It can't be any simpler or functional than that!

There's more too! The crank-knob (see L1 above right) and the larger secondary spur gear (see L2 above right) have large [black] locking thumb screws - no tools required. By tightening the thumb screw on the large spur gear (L2), and loosening the thumb screw on the crank knob (L1), you engage a 6 to 1 gear-reduced control. Conversely, by loosening the thumb screw on the large spur gear (L2), and tightening the thumb screw on the crank knob (L1), the focusing knob on the left side of the M4 or M5 focuser becomes the same as the right focus knob, like any other standard two-knob focuser. And there's more! Either motor (DC servo or stepper) drives the large main spur gear directly connected to the Crayford shaft (see REDUCTION 1, above left). More about the importance of dual DC servo or stepper motor control below. Ain't gaudy wonderful!

TRI/QUAD-FOCUSERS

M2 & M3 (above left) have Tri-Focus, M4 & M5 (above right) have Quad-Focus

See specifications list above for reduction ratios, etc.

[top of the page]

Commercial MacroGlide & MasterGlide Size/Mass Comparisons

No words are really needed here, but do note the size of the Crayford bearings, where applicable.

Miniature Slot Car Bearings vs Large-Diameter Precision Bearings

A penny for your thoughts. Size does matter!. These pictures illustrates the difference in size between the bearings used in all other Crayford focusers (that I know of) compared to the bearings in VSI focusers. What you can't see in the picture is the lack of quality, but we'll get to that later.

Anyone can purchase these miniature slot car bearings on the internet for about a dollar or two each in quantities of 10, as pictured above. Dealers can purchase them for under $1 each in bulk quantities, so why do Crayford focuser dealers [gladly] sell you a replacement bearing for $25? Ouch! I hear that people need to replace them frequently. These slot car bearings are not even designed for loading. They are designed for hi-speed rotation, usually around 20,000 to 80,000 rpm. Whoa! That's fast! That means that their tolerance has to be very low to accommodate those extreme speeds. In other words, sloppy bearings designed for speed, not precision. Slot car bearing static load is [at best] around 13 lbs. and their dynamic load handling is around 44 lbs. That rating is for a precision bearing of the same comparable size because that is the only reference I could find. Slot car bearings don't even list their load bearing capacity, probably because they are way below the numbers that I referenced. What do you want for a dollar?

As you can see, almost two of these miniature slot car bearings can be dropped, side by side, through the center hole in a VSI bearing. VSI has always used precision radial, chrome steel ball bearings in all focusers since day one over 20 years ago. For simple comparison, each VSI bearing has a static load capability of 310 lbs. (slot car = 13) with a dynamic load capability of 740 lbs. (slot car = 44). That load rating is times four [bearings] when it's on your focuser. And precision radial ball bearings have much tighter tolerances because they are not designed for crazy hi-speed operation - a few hundred to a few thousand rpm max.

What kind of rotational speeds are we talking about for a Crayford focuser? Fractional, less than one, rpm. So why use hi-speed, low tolerance bearings in a Crayford focuser?  Maybe you would say cost. The large precision radial ball bearings I use are around $4 or $5 each. Not cheap, but not overly expensive either. Maybe it looks better to hide the bearings inside the focuser's housing? I would hide them too if they were that small. If the bearings were hidden inside the housing, they could even buy cheaper open-race bearings instead of shielded or sealed bearings. All VSI bearings are not just shielded, they are sealed so zero contamination can get inside the bearing's race, whether they are exposed to the elements, or not.

Another poor design on most Crayford focusers is their one-sided bearing mounting, using a shoulder screw. This causes the bearing to flex from the unsecured [screw-head] side of the bearing. VSI focusers use a 3/8" diameter stainless steel (SS) pin that is secured by SS screws from both sides of the bearing directly to the focuser's housing. This super secure bearing mounting provides ultra-secure, zero flexure movement of the travel tube. There are dozens of other reasons why VSI focusers are superior, expecially in load handling, to all other Crayford focusers on the market. This is just one more reason.

VSI's Dual Control Hand Paddle

Our Mega-Power Dual Control hand paddle incorporates individual IN/OUT speed-torque control for balanced load even at zenith positions. Just turn the knob below the push button (see picture at right) to change the speed of the IN travel of the DC Servo motor. Turn the other knob to control the OUT travel speed.

Other hand paddles have one knob to control both IN and OUT speed, so when you are observing near the zenith and push the IN button, your motor strains to lift the load at reduced speed and torque, and drops the load at a much faster speed when you push the OUT button.

With VSI hand paddles, you can balance your load by simply adjusting the two individual speed control knobs. Your IN/OUT speed can be precisely controlled for any load and any observing elevation from horizon to zenith with a simple turn of a knob(s).

This new VSI circuit design instantly starts the rotation of the motor, even at it's lowest speed, as soon as a button is pressed. No more time lag between direction changes, like other hand paddles. This new paddle delivers super-smooth, "analog" speed control that is mechanically and electronically near-indestructible.

This paddle is used to control our DC servo motor only. It will not operate the Robo-Focus stepper motor. Uses 120vac wall-wart type power supply (included when ordering appropriate focuser package) or 12vdc car cigarette lighter (optional). Operating voltage: 12 to 24vdc.

The Importance of Dual-Motor Controlled Focusers

VSI motorized focuser models offer two types of motor control - DC servo and stepper.  In fact, VSI focusers offer the only dual-motor control on the planet (that we know of), allowing both motor types of remote focusing control with a fast and easy "slide-out/slide-in" motor switch-out (see picture at left). You can also disengage either motor from the drive train for hands-on manual focusing with the instantaneous turn of a knob.

Why do we offer these exclusive motor features? Because DC servo motors are analog and introduce no vibration or noise into the drive train like autofocus stepper motors, which are inherently noisy and cause step vibration (even when microstepping). DC servo motor control offers smooth, remote hands-off eyepiece focusing via our new [super powerful] RAMPING hand paddle, that is custom designed and built by Impulse Engineering exclusively for VSI (see picture above right).

On the other hand, stepper motor control offers wonderful computer controlled autofocus for astroimaging, but is not capable of vibration-free driving of the moving tube, especially at resonant step frequencies, which cause your star images to jump all over the place when attempting to focus, making it impossible to remote eyepiece focus. This is why autofocus computer subroutines stop focusing, take a focus image, then do it all over again until perfect focus is achieved - a time consuming process, but acceptable. Although remote push-button control is offered on autofocus electronic hardware packages, via two push-buttons, you really can't use it for anything more than repositioning the focuser's moving tube to begin autofocus computer controlled focus procedures. It is simply a convenience feature. You can't do simultaneous visual eyepiece focusing with a stepper motor because it induces vibration when activated.

This little known motor control fact is very important when considering the purchase of a focuser that you want to use for both visual, remote eyepiece focusing and computer controlled astroimaging applications. You can't have hands-off remote eyepiece focusing and computer-controlled autofocus for astroimaging, unless you have a focuser with dual-motor control capability. This is something that the other single-motor focusers on the market don't want you to know, until it's too late. Unfortunately, this lesson is usually learned the hard way. Even though this info, that you are reading now, is buried [here] at VSI's Features link, you may be one of the lucky ones, if you were seriously considering a dual-purpose focuser for both remote visual focus and computer-controlled astroimaging.

Re-Engineering & Improving the Basic Crayford Design

Although most Crayford focusers on the market today utilize VSI's [original] central pressure point design, we continue to stay ahead of the game by continually improving our products, as noted by the myriad of improvements to our focusers over the decades. VSI has always maintained only the basic Crayford concept. Everything else has been thrown out the astro-portal and redesigned from the ground up. We have modified the four-bearing support platform by supporting the bearings from both sides (a feature others have copied for many years now), using hardened steel drill rod shafts and a complete cylinder instead of a cylinder section, providing more than twice the stability compared to single-end supported, bearing mounting systems. We have also made the entire structure more massive, and increased the typical bearing size (approx. 1" diameter bearings). The drive shaft support mechanism has also been re-engineered to eliminate the weak, flimsy, distortion prone standard drive shaft mechanism (see above diagrams) provided by many other manufacturers. The above left diagram explains the internet reports of ball bearings literally exploding due to over tightening a poorly designed drive rod tensioning mechanism. If the two drive shaft bearings remain fixed perpendicular to the drive shaft, while the shaft itself is allowed to warp [away from perpendicularity] from over tightening, then the bearings will bind causing locking of the drive shaft and danger of an exploding bearing. Even replacing the ball bearings with bronze bushing-type bearings will not eliminate locking or pinching of the drive shaft from normal tightening of the tension mechanism. Increasing the diameter of the drive rod will relieve some of the warping, but it will also give you a much coarser [ratio] movement of the tube, which is not acceptable, at least at VSI. The drive rod diameter must remain small to provide fine control of the moving tube. VSI uses a 1/4" diameter steel drill rod (concentric to 0.0004") machined down at the center to 0.15" providing a relatively fine focusing ratio of 0.47" of tube movement per revolution of the focusing knob.

To apply force at the center, instead of at the outer ends of the drive shaft, VSI uses two expedient and economical virgin Teflon pads backed by two adjustable, large Allen head set screws. Engineering studies have shown that, in this application, center mounted Teflon pads provide an inexpensive method to totally eliminate drive rod warpage and inherent concentric machining errors while allowing the user to adjust and apply a much higher FORCE between the drive rod and the moving tube, without warpage concerns. The more force you apply to virgin Teflon, the more "slippery" it becomes, making it an ideal and economical substance for Crayford drive rod applications. With the available increased force applied to the drive shaft, you can eliminate the typical "sloppy" action notorious to previously ill-designed Crayfords providing a more positive "rack & pinion" action, and a much higher leveraged load handling capability for astroimaging, etc.

A Brief History of the Crayford Focuser

The Crayford Focuser was invented by English amateur John Wall of Dartford, Kent, England in the early 1970's. His inspirational focuser was demonstrated at the Crayford Manor House Astronomical Society and described in the Journal of the British Astronomical Association (Feb, 1971). Also, several examples were published in Model Engineer magazine (May, 1972). Curiously, the Crayford focuser is not named after it's inventor, Mr. Wall, but after the Crayford Manor House itself. Even more curious is that he never patented the design, which rendered it unpatentable over the years because of his existing published "prior art." Others have acquired patents for various minor modifications to the basic Crayford design, but such patents pale in the light of the revolutionary, original Crayford focuser implications. FYI, an interesting article on the Crayford focuser appears in Sky & Telescope magazine, Gleanings for ATM's (Sept, 1972, p182). Mr. Wall's original Crayford focuser appears at right (courtesy Sky & Telescope magazine).

I would personally like to thank Mr. Wall for magnanimously donating his invention, the Crayford focuser, to the astronomical community. The Crayford focuser, and Mr. Wall, will live forever in the hearts [and hands] of amateur astronomers throughout the world. It is the only focuser mechanism that offers true zero-flexure tube movement. In my humble opinion, it is the finest, most ingenious focusing control mechanism ever created! - PVS

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2" MicroGlide Docking Focusers

Manual & Auto-Focus Stepper (digital) Motor Control

Without Comparison, the Finest Feature-Packed Focusers on Planet Earth

If you're THINKING  about a FOCUSER, THINK GLIDERS for the FOLLOWING REASONS

Mount any VSI Focuser to any Scope - Not just Meade & Celestron

AP, Borg, DFM, OGS, RC Optical, Takahashi, TeleVue, TMB, Vixen, etc., etc. - Just Call VSI

Features & Specifications: MicroGlide Focusers (2" format)

VSI's [2" format] MicroGlide Focuser (patented) is the first [ever] 5th-bearing Crayford design. This revolutionary new encapsulated, five radial ball-bearing, frictionless design provides slippery-smooth, precision moving tube travel that is beyond anything you have ever experienced - guaranteed, or your money back!

The patented Van Slyke drive (VSD) is hidden inside the focuser's small aluminum box. This new focusing mechanism will not be disclosed. However, the focusing action is controlled from a precision Mitutoyo (made in Japan) micrometer head. This micrometer head incorporates indices of 0.001" and can be interpolated to 0.0001" with ease, and the moving tube has a full half-inch of travel - it doesn't get any better than that! And this focusing position accuracy is repeatable, so you can use it for astroimaging, or any repetitious focusing task.

MicroGliders include our exclusive Finger Spinner (pictured left). Simply insert your index finger in any one of the six [inverted hemisphere] ball cavities and spin away. You can't do this with ordinary focusers, with less-sensitive tactile control, because you would have your scope/image wobbling all over the place/sky. Only the ultra-sensitive, no-resistance, action of the MicroGlider's micrometer head, coupled with the finger spinner, would allow this tactile finger spinning action with ease. The finger spinner also increases your resolution and torque, making it that much easier to manipulate your focusing position manually. Ease of movement and ultra-sensitive tactile control doesn't get any better. And, for changes in focus position, just spin the finger spinner with your index finger. It doesn't get any quicker, either!

Many other focusers are either too coarse or too fine, or they offer both coarse and fine control knobs, but neither approaches that manual/visual "sweet spot" of focus control. What good is a focuser that has coarse and fine control when both actions are either too coarse one way, or too fine the other? VSI has always gone to extra [machining] effort to provide that special ratio that visual astronomers want - usually on the fast side of fine. Not too coarse, so you can't achieve true visual focus, and not too fine, where you can't achieve focus with a single [rotational] movement of your wrist. Visual astronomers, who have experience with other focusers, have told me that the other dual control focusers are way too coarse and their fine control is way to fine for visual work. They say that VSI focuser's single control knob is just right for visual/manual control. Our MicroGlide focusers also provide the finest autofocus ratio available for astroimaging, where one motor step = 0.0000069" of tube travel. This equates to the finest autofocus control on Planet Earth, by a very wide margin! We dare you to even come close to those autofocus specs anywhere else. The next closest motor controlled autofocus ratio is [you guessed it] our MasterGlide focuser at 0.000052" of tube travel per motor step, which is also finer than any other autofocuser on the market. This simplifies your autofocus decisions substantially, either MasterGlide or MicroGlide. Note that the manual microfocusing tangent arm, on our MasterGlide focuser, is way beyond ultra-fine at 5/1000" tube movement per revolution of the manual control knob, but it is intentionally designed that way for hands-on micro changes in focus for astroimaging, a different focusing situation all together.

VSI offers a unique MicroGlider strategy resolving the profile problem regarding focusing range/travel. MicroGlide Omicrons (MGF2) have interchangeable (optional) drawtubes that have a 2.25" outside diameter for zero profile insertion, while the Omicron's moving tube has a 2.25" inside diameter. This combination allows the entire drawtube to be inserted into the focuser's moving tube with only the locking thumb screws protruding above the tube. This solution to the profile problem still allows full 2" format usage with the drawtube fully inserted in the focuser's moving tube. Profile problem solved! Conventionally, with a 2" OD drawtube, you would have at least 2" extending beyond the moving tube to accommodate 2" format barrel nose eyepieces, etc. This would be OK, if you have the profile to spare, but an unacceptable profile loss when considering limited back focus refractors and other optical configurations designed with limited (or should I say "short-sighted") back focus.

You have three MicroGlide model choices: 1) Our Epsilon MGF1, without the built-in drawtube for SCTs such as Meade/Celestron, where your SCT already has long-range primary focusing built-in, and you need a sturdy secondary short-travel focuser. For your consideration, you could also use our Omicron docked to your SCT with our 2" SCT drawtube for added redundant focus range, simply to increase your convenience and versatility. 2) Our Omicron MGF2, with built-in long-range drawtube capability - up to 12" of travel! This model is designed for refractors, catadioptrics, etc. as a primary focusing device for long changes in back focus, while still maintaining superb micro-focusing capabilities. Consider longer drawtubes with scopes that allow the drawtube to be extended through their visual backs (see picture above, far right). With catadioptric scopes, the center perforation in your primary mirror would have to be 2.25" or larger to accommodate a long drawtube being inserted through your primary mirror. While your MicroGlide focuser only has an actual 0.5 inches of focus travel, you would then have up to 12" of focus range (use our custom drawtubes offered below) by simply loosening your thumb screws and push-pulling your drawtube (see picture above). In fact, for changing your coarse focus point, the push-pull method is the fastest available. Simply push/pull to ballpark your new focus point and fine focus by turning, or spinning, the micrometer head. A fast, simple, elegant, and functional solution to having your ultra-fine focus control (cake) and coupling it to an extremely long focus range (eating it too). 3) The coupling focuser MGFCO is offered in three formats for AstroPhysics, Takahashi and Meade refractors. It is simply a coupling with a built-in focuser that can provide manual or autofocus without modifying your scope's existing manual focuser.

Speaking of cake, here's some "ice cream" to top it off. MicroGliders offer motorized AUTOFOCUS positioning for astroimaging too! VSI offers a MicroGlider stepper motor mounting hardware kit (MTH1) that provides simple and elegant "turn of a thumb screw" manual or motorized operation. Autofocus stepper motors are mounted to the MicroGlider using our exclusive 1/4" ground and hardened steel caliper rods, accurate to 0.0001" in diameter. Our precision machined, fixed caliper clamp, mounted on the motor, rides the rod [back and forth] providing zero [and I do mean zero] backlash (see picture at left). No "hard-wired" motors, no dysfunctional friction clutches, no backlash inherent cog pulleys, no "flip-flop" [gravity sensitive] SCT mechanisms, and no "slip & slide" rubber band drives. This simple stepper motor mounting mechanism offers you the ability to easily switch from autofocus to manual control [or vice versa] as fast as you can loosen, or tighten a thumb screw!

The MASTERGlide QUAD-LOCK feature is incorporated on all MICROGlide focusers (see picture at right). This exclusive VSI locking feature is a super-solid coupling between the focuser's moving tube and your 2" barrel nose eyepiece, diagonal, or accessory. Focusers have always been designed to support a single diagonal and eyepiece using only one or two thumb screws, which was adequate for lighter loads. When imaging trains emerged, this basic philosophy was never upgraded to support these heavier loads. Since the beginning of focuser design, locking thumb screws have always been a weak link regarding astroimaging. Many focusers have only one locking thumb screw, which is adequate for visual observing with a single eyepiece or even diagonal and eyepiece. All higher quality focusers have two thumb screws that should be opposed by 90 degrees for maximum holding power. Many are opposed by 120 degrees, which does not lock a 2" format barrel nose at the maximum [perpendicular] support angle (similar to Crayford bearings which are opposed by 120 degrees instead of the more supportive 90 degrees, but that is another story). Dual thumb screws are not adequate for even the simplest imaging train, let alone a leveraged extended one that can weigh 3 to 4 times as much as a simple 2" format diagonal/eyepiece combination. VSI's exclusive QUAD-LOCK feature offer FOUR thumb screws that securely support the most elaborate imaging trains. QUAD-LOCK's holding power is equivalent, or superior, to the best threaded couplings. And, this new feature is not overkill for astroimaging. It is a necessity to guarantee zero-flexure at this extremely critical junction.

The perfect marriage (if there is such a thing) between focuser and rotator! Combining our manual Zerotator and MicroGlide focuser (pictured at right) creates a rock-solid, stable rotating platform for astroimaging or just rotating your diagonal or Hexagonal to a more comfortable viewing position. The radial ball bearing loaded Zerotator can handle any load you stack on it, because it was designed to hold your entire imaging train - focuser, optical manifold, CCD camera, etc., etc. And it has a 2.75" internal clear aperture so vignetting is not a problem.

You may also focus manually, without removing the motor, by simply loosening the single SS thumb screw (see pictures above), which disengages the motor shaft, allowing you to rotate the finger spinner knob by hand. But it is easier removing the motor to acquire full access to the spinner knob. However, this manual ability would be very convenient when attempting to acquire ball-park focus without having powered motor-slewing capability (i.e. the motor isn't plugged in, no power supply, your computer isn't "up" yet, etc.). As we know, an extremely gear-reduced stepper motor's drive shaft does not turn unless it is under power. Removal of the motor is accomplished by simply loosening the thumb screw (no tools involved), and sliding the motor off the two shafts (one motor shaft and one 1/4" alignment shaft). To replace, slide the motor onto the MicroGlider and tighten the thumb screw (see pictures above). For more info, see AUTOFOCUS link.

VSI MicroGlide focusers are designed to dock with any scope on the market, either with our standard docking adapter rings, or custom machined rings. Our most common docking ring installs our MicroGlide focusers on the current generation of Meade/Celestron Schmidt-Cassegrain telescopes (smaller than 10") that focus by moving their primary mirrors (which always have an unacceptable amount of lateral image shift when focusing), and accept accessories via their standardized 2"-24tpi threaded visual backs. However, MicroGliders can also be installed on any scope utilizing our other docking rings. MicroGliders have the shortest profile of any focuser (less than 2"), so you can easily piggyback an [ultra-fine focus] MGF on the output of your scope's stock [coarse] focuser, and have back focus to spare for a Slider and a CCD camera (see the Takahashi pictured at right). Note this is the new, extended back focus Takahashi. Not the old "no-back-focus" Taks of the past, which would barely accept a standard diagonal and eyepiece before exhausting their [very limited] back focus. For more info on this rock-solid, slick (or should I say "Slyke") Tak imaging train installation, see User Installations link. If we don't have a stock docking ring for your particular scope, we'll custom machine one. All docking rings have a circular dovetail cut into the OD of the ring to securely lock into the MicroGlider's housing via three 8-32 set screws (see DOCKING ADAPTERS link).

WARNING: Be aware that all [so-called] Crayford focusers, are not really Crayford focusers. Deceptive advertising by many dealers, trying to take advantage of the Crayford's reputation, offer Crayford-type, Crayford-like or Crayford-style focusers that have very little to do with the true Crayford design. NO radial ball bearings, NO zero-image-shift, NO fluid motion, NO ultra-tactile sensitive control, NONE of the above functions that made the Crayford the finest precision focuser on Planet Earth. These non-Crayford focusers typically use plastic pads to simulate Crayford bearings and other inferior construction techniques that deminish the Crayford name. Only a focuser that uses four (or five, like VSI's MicroGlider) precision ground steel, radial ball bearings can [rightfully] be called a Crayford focuser. - PBVS

MicroGlide Omicron Focusers & Sidewinders  - the Perfect Marriage!

MicroGlide Omicron focusers and Sidewinders, equipped with autofocus, create the ultimate dream imaging train for professional and amateur astronomers alike (see picture at right). Although the imaging train pictured at right is configured to support the large-chip SBIG STL, it is shown without the CCD camera for clarification. However, all you would need to do, to complete this specific imaging train, is screw on a STL camera, autofocus the CCD camera (utilizing the stepper motor mounted to the Omicron, see picture, far left), push/pull parfocus all your side ports, and begin imaging.

Why try to "Mickey Mouse" your scope's existing focuser with an aftermarket autofocus system, just to find out that the step to tube movement ratio is too coarse? Simply couple an Omicron focuser to the output of a Sidewinder and you achieve the finest autofocus ratio, by a factor of 10, available anywhere. Use an Omicron focuser, with our new SBIG STL 2.156"-24tpi insert tube adapter (Item #AMGST, pictured upper left, also see SIDEWINDERS link, ADAPTERS link) and you achieve a full 2" internal clear aperture (SBIG recommends a minimum of 1.95" for their STL). To facilitate docking your Omicron to the rear camera port of the Sidewinder, we have created a new double flanged port ring (Item #MR2729, pictured lower left, also see DOCKING ADAPTERS link above). This port ring also saves the cost of a second threaded port ring, and decreases profile by about a half-inch compared to using two redundant threaded port rings. Although this Sidewinder/Omicron combination has been optimized for the new chips, that are too large for the existing 2" format, you could also use the Epsilon with the Sidewinder to utilize any smaller chip size CCD camera on the market. You are only limited by your imagination.

With the 3" profile of the Sidewinder and the 2" profile of the Omicron, you have a 5" overall profile, which is short enough to work with any SCT or extended backfocus refractor, like the Takahashi TOA series. Note that all the side ports have been parfocused to match the extended 2" profile of the Omicron. In fact, a 2" format eyepiece, inserted directly into the Sidewinder's top port, is just about parfocus with the Omicron installed on the Sidewinder's rear port. Also note that the side pick-off port can be extended with a 1.25" diagonal and achieve parfocus with your imaging CCD camera. With the diagonal installed, you also provide a more comfortable guiding position. Or you could also auto-guide with a SBIG STV CCD camera, etc. Enjoy the possibilities, because we all know that it's just as much about the cool gear, as it is about the imaging. It doesn't get more outrageous than this!

About the MicroGlide [in-line] COUPLING Focusers

I believe this endeavor to be another VSI first - an in-line coupling that focuses. For short, I call it a Co-Focuser. It is simply a 2.7" male threaded coupling on one end and a 2.7" female [same size and thread pitch] threaded coupling on the other (see picture below). It is basically a re-machined Epsilon/Omicron with threaded couplings. The Co-Focuser operates just like its predecessors, the Epsilon and Omicron. Turn the micrometer knob and the knurled thread [top] end of the focuser moves outward (see picture left), providing a full half-inch of travel. Overkill range for a secondary focuser.

The internal clear aperture is a full 2.25 inches (see picture at right). More than enough for today's gigantic CCD chips. All the newer APO refractors are shortening their tubes to provide extended back focus - it's about time too! This allows you to take advantage of all the cool imaging train accessories available today - like VSI stuff. This new 2.7" co-focuser is basically identical to the above 2" MicroGlide 1 & 2 in focusing operation and tube movement, except the outer housing moves when focusing, instead of the inner tube. You read it right, the first moving outer housing focuser! This new revolutionary reverse-focusing operation offers superior, rock-solid outer-housing movement over conventional [inner] moving tube focusers. The only other difference is the focuser's input and/or output, which is threaded to match either an Astro-Physics 2.7"-24tpi thread (shown), a Takahashi 72mm-1mm thread, or a Meade 2.7"-16tpi thread. Your choice of formats. Base [threaded reverse format] docking port ring may be included (at no charge) depending on remaining stock/format availability.

Actually, the most important reason for the creation of this co-focuser is autofocus. Why attempt to modify your existing focuser for autofocus when all you have to do is screw on a co-focuser equipped with our hardware kit and our Robo-Focus stepper motor. After all, the large-format rack & pinion focusers on those APOs are usually pretty fair quality (although not compared to a Crayford), so why replace it or try to "Mickey Mouse" it with an aftermarket universal motor mounting kit. None of these new APO manual focusers are easily modified to provide autofocus. Even if you effectively modify your existing focuser, it is usually too coarse to provide adequate autofocus stepper motor ratios, which means you end up with soft astroimages. And these aftermarket universal kits, for mounting a stepper motor to your focuser, leave a lot to be desired in function, accuracy and rigidity, not to mention style and a clean looking installation. Remember, our MicroGlide focusers, including our new co-focuser, offer an insane stepper motor to tube movement ratio that is a factor of ten finer than any other autofocuser on the market - one motor step = 0.0000069" of actual tube travel! And that's not overkill. It's just a ratio that will make all your astroimages as razor sharp as is mechanically and optically possible.

Of course, you don't have to purchase a 2.7" co-focuser for autofocus only. You may just want a super-fine secondary focuser on your refractor to use in conjunction with your scope's existing, coarse primary focuser. This co-focuser is so ultra-fine that you can achieve perfect manual astroimaging focus and return to the exact [repeatable] "in-focus" position every time using the micrometer head's built-in analog indices, and there's zero backlash.

Some Ancient History about the "NEW" MicroGlide Focuser

Actually, you may have seen a variant of this focuser at star parties or, coincidentally, you may even know someone who has one of VSI's ancient "Micro-Gage" focusers. If you have an old issue of Sky & Telescope magazine, from October 1998, take a look on page 85 and you'll find the original version of this new MicroGlide focuser (copy of 1/2-page display ad pictured at right).

I even had the foresight to begin patent applications (note the patent pending in the ad, lower right corner). Well, as you know, patents take many years to become reality, and many years have passed since then, so the design is now officially patented. Unfortunately, I discontinued it after the first short production run because I simply wasn't satisfied with its operation or performance. Oh, it was an okay focuser, but I don't offer a product that isn't up to my own personal standards of excellence. It's simply a VSI philosophy/trademark of excellence that you can always count on.

The old Micro-Gage needed work to make it a "true" VSI product. And, back in the early days, time wasn't on the Micro-Gage focuser's side. I was on a quest to create the "perfect" product and, in the process, I discontinued many lines of redundant [if not Meade-iocre] products (Flippers were discontinued and replaced by Sliders, Super Power and Micro-Gage focusers were replaced by Monsters, etc.) on a massive scale. Now, Monsters have been replaced by MasterGlides, etc. I could then concentrate on a few good products (like a few good men) that were functional, feature packed, simple in design, and [of course] indestructable. If you haven't been there, believe it or not, simplicity and functionality are very difficult combinations.

Unlike the massive MasterGlide focuser, which was intentionally designed for larger scopes, it was finally time for a new focuser design that could be optimized for smaller scopes, like 8" SCTs and scopes of similar proportions, and offer an autofocus (co-focuser) capability to your existing scope's focuser by only adding 2" of profile to your existing imaging train. So the new MicroGlider (old Micro-Gage) finally became the perfect solution to creating a smaller format, super versatile, ultra-sensitive focuser that also does autofocus.

The new MicroGliders are literally like no other focuser ever created. When you experience the elegant purity and simplicity of this [ultra-sensitive tactile contact] focuser, you will be convinced of its worth as a pre-eminent new movement format that, hopefully, will be considered adjacent to the rack & pinion, the helical, and even the formidable Crayford. This totally new moving tube mechanism (aka the Van Slyke drive) is nowhere near any of the other common, industry-standard designs. And it's extremely comparable in operation (i.e. the renowned coined phrase that denotes the Crayford - "zero-image-shift") to the Crayford, which I consider to be the most simple and functional focuser operating design ever created (thank you John Wall), when done correctly.

Unfortunately, even the venerable Crayford can be "butchered" by those who build the cheapest products humanly possible - but the price is good! Actually, VSI products are priced only slightly above other mediocre products, but when you consider a build-quality and features that are at least 10 times greater, you begin to understand VSI's truely wholesale marketing philosophy that offer incredible savings, direct to you, the customer - such a deal! - PBVS

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MicroGlide Docking Port Rings

Docking adapter required for all MICROGLIDE Focusers except MGFCOs
Docking Ring, 2"-24tpi for commercial SCTs, Item MR224: $49
Coupling Ring, 2.7" to 2.9" MicroGlider to Sidewinder, Item MR2729: $69
Docking Ring, 2.7"-24tpi Astrophysics refractor, Item MR2724: $69
Docking Ring, 2.7"-16tpi Meade refractor, Item MR2716: $69
Docking Ring, 56mm-0.75mm thread pitch, Takahashi, Item MR56: $49
Docking Ring, 72mm-1mm thread pitch, Takahashi, Item MR72: $69
Docking Ring, 90mm-1mm (replaces existing focuser, Omicron only), Takahashi, Item MR90: $99
Docking Ring, 3"-24tpi (replaces existing focuser, Omicron only), TeleVue, Item MR324: $99
Docking Ring, 85mm-1.5mm thread pitch, TMB 3" focuser, Item MR85: $99
Docking Ring, 110mm-1.5mm thread pitch, TMB 4" focuser, Item MR110: $149
Docking Ring, 88mm-1mm (replaces existing focuser, Omicron only), Vixen, Item MR88: $99
Docking Ring, 3.25"-16tpi, Meade Large-Format SCT, Item MR325: $99
Docking Ring, 3.29"-16tpi Celestron Large-Format SCT, Item MR329: $99
Docking Ring, 4"-16tpi Meade 16" SCT, Item MR416: $199
Docking Ring, 4" x 4" Sq. (Omicron), Newt/Dobs, Item MR44: $149

Mount any VSI Focuser to any Scope - Not just Meade & Celestron

AP, Borg, DFM, OGS, RC Optical, Takahashi, TeleVue, TMB, Vixen, etc., etc. - Just Call VSI

QUALITY ASSURANCE NOTE: It has come to my attention that others use less than adequate coupling methods on their products that induce flexure. They look very similar to VSI's exclusive docking/coupling systems. They are NOT! VSI's exclusive docking/couplings are not like any other flimsy, flexure-ridden connections used on other products. A good analogy would be a comparison between a (less than) $50 and a $300 (and up) rifle scope. The lesser rifle scopes looks identical to the more expensive ones but, in operation, the differences are very apparent, optically and [especially] mechanically. Let the buyer beware, you receive quality and functionality only when you are willing to expend an appropriate dollar amount. VSI's proprietary flared flange (circular dovetail) docking inserts have extremely thick-wall construction and are locked in place by three set screws opposed by 120 degrees. When you tighten these set screws against this special [angled] flange, it not only pushes directly against the insert ring, but it also pushes laterally to compress the ring inwards against external and internal shoulders, which locks it in place like a good weld - rock-solid! - PVS

DOCKING RINGS for your MicroGlide Focuser

VSI's MicroGlider docking rings (MR224 pictured at right) allow your MicroGlide focuser to be used on any scope, literally. Even Newtonians and Dobsonians. Select your docking ring adapter above or, if we don't offer a docking ring adapter for your scope, then just send us a male or female threaded part that matches your visual back's focuser threads and we'll custom machine one for you.

MicroGlide focusers are designed to be used with their respective docking rings, individually priced above. This docking ring option provides your MicroGlide focuser with more versatility than any other focuser available today, and gives you a selective choice of rings to dock your MicroGlider to any telescope on the planet. Even Newtonian and Dobsonian scopes. You can also switch MicroGlide focusers between different scopes, or retain your MicroGlider when you sell your old [say SCT] scope and use it on your new [say refractor] scope, by purchasing a docking ring adapter or possibly drawtube upgrade.

HINT: When installing a MicroGlide focuser on your 10" or larger Meade/Celestron SCT, consider using one of the larger (internal clear aperture) MR325, MR329 or MR416 instead of the smaller MR224. You can then simply bypass this [now extinct] reducer that comes with your SCT. By attaching the MicroGlide directly to your SCT's visual back, via one of the larger format docking rings, you prevent vignetting caused by your existing reducer's small 2"-24tpi aperture. Note, this is not a consideration with MasterGlide focusers because they [only] dock directly to these larger format visual backs, naturally eliminating vignetting.

COMMENTARY

The above adapters are all non-standard proprietary formats from individual manufacturers - no industry standards exist. Why can't these manufacturers adopt the closest standard set by their predecessors? There can only be two excuses; they're lazy or arrogant, or possibly both. Look at the three Tak, TMB and Vixen adapters above (90, 85 & 88mm). They are all within 2 or 3 mm of each other (I even used the same picture for all three because you couldn't see the difference anyway, and they're not the only ones duplicated above). Why? Look at the two Celestron and Meade large-format adapters. One is 3.29" and one is 3.25" in diameter. Look at the two AP and Meade 2.7" adapters. Meade changed the existing 2.7" AP thread standard from 24 to 16tpi, but the 2.7" diameter remained the same. Again, why? Both of these non-conformity issues are Meade's fault for not adopting the existing Celestron and Astrophysics standards already established. And now SBIG has created a new 2.156"-24tpi proprietary thread standard for their large-chip CCD camera. Watch and see, no one else will adopt their thread configuration. They'll all create their own proprietary standard and you'll have a half-dozen different diameters and thread sizes that are within a few millimeters of each other, again. Do these manufacturers care about their customer's inconvenience and added expense? Never even crossed their minds! This kind of "diametrical dysfunction" creates confusion and costs you money, and it's totally unnecessary. Just wanted you to know, so you can take your own action  - or not? - PBVS

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MicroGlide Drawtubes for your MGF2

DRAWTUBES for your MicroGlide Omicron Focuser

VSI's 2" inside diameter drawtubes for Omicron focusers [only] are available in various lengths to accommodate any scope, from SCTs to refractors. Calculating which length is right for your scope is easy. Just determine how far a 2.25" outside diameter tube can be inserted into your telescope's visual back, then add the Omicron's overall profile of 2.5 inches. If it's an SCT, you would probably want to use our Epsilon which has no built-in drawtube capability, but you could also use our Omicron with a standard 2" SCT drawtube (DWT2). Remember, if the Omicron is being used as a secondary focuser on an SCT, you don't really need any drawtube extension but, with the Omicron installed, you will acquire an extra [redundant] inch plus of back focus adjustment, without sacrificing profile. However, you can not use longer than 2" drawtubes if you are installing your Omicron on a commercial SCT.

With refractors, or any other non-SCT, that have no obstructions in their visual backs, a longer drawtube should be used to obtain maximum backfocus range. In many cases, a longer drawtube is absolutely necessary because you have no primary focus to change your back focus. Your long drawtube gives you the focus range you need to accommodate any observing or imaging profile. Just don't get your drawtube too long or vignetting may occur, although you do have a full 2" clear aperture. If you have a [say] fast refractor, consider the shortest drawtube you can utilize effectively. Don't just "pop" for the longest one available.

VSI also offers a special threaded drawtube (item AMGST below) specifically for the SBIG STL11000 CCD camera (pictured below left). This threaded 2.25" OD x 2" ID insert drawtube replaces the standard drawtubes. Installing this threaded drawtube provides the necessary 2" internal clear aperture reguired for the STL's large chip. 

IMPORTANT: Omicron focusers are designed to be used with these optional drawtubes, individually priced below. This drawtube option provides your Omicron focuser with more back focus versatility [and the shortest profile possible] than any other focuser available today, and gives you a selective choice of back focus travel, depending on which drawtube you choose. You can also switch MicroGlide focusers between different scopes, or retain your MicroGlider when you sell your old [say SCT] scope and use it on your new [say refractor] scope, with only a drawtube and ring adapter upgrade. Without the optional drawtube inserted in your Omicron focuser, you'll need non-standard 2.25" barrel nose eyepieces [that don't exist], and you won't have any focus range, except for the intrinsic half-inch travel of the micrometer head itself.

[return to home]

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