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GSO 2' Crayford Focuser for SCTs - Single Speed

5.0 (4 Reviews) Read Reviews Write Review
Brand GSO
Part Number PAF-GS-SCT-SS
Availability available

Product Info

Manufacturer Description

Many users find the primary mirror focusing mechanism of Schmidt-Cassegrain telescopes (SCT) cumbersome to use. There is some amount of image shift and precise focus cannot be found easily. This is inconvenient for visual use and a serious problem for astrophotography. GSO's (Guan Sheng Optical) latest Crayford focuser model is a gorgeous, all-black, rotatable focuser for Schmidt-Cassegrain telescopes that elegantly solves these problems.

CNC machined from aluminum and anodized black, this focuser will screw on to the rear cell of any* SCT telescopes sold by Meade and Celestron having a standard SCT thread. The standard SCT rear cell thread is 2" diameter male thread with a thread pitch of 24TPI (threads per inch).

This single-speed Crayford focuser is a joy to use and you will wonder how you ever lived without it once you install it! By design, SCT Crayford focusers eliminate the annoying backlash and image-shift that plagues many SCTs. You will experience very smooth and precisely controlled focuser motion. 

The inner drawtube glides on 4 precision bearings and a roller shaft. The inner barrel is baffled and painted a flat black to minimize reflections for maximum contrast. This barrel is also black anodized and features a laser-etched mm (millimeter) scale.  It provides 1" of focus travel which is more than adequate for SCTs. You first use your SCTs focusing knob to achieve coarse focus and then switch to the Crayford focuser for finer focus and control. Depending on your range of eyepieces and accessories, you may never need to touch your SCT's main focuser again!

The 2" focuser barrel features a brass compression ring and can accept standard 2" refractor-type diagonals and other accessories. Also included is a 1.25"-2" adapter with brass compression rings and threads to accept standard 2" filters. This deluxe model features a 360-degree rotatable ring that allows you to orient the focuser (and hence your diagonal/eyepiece) to the most comfortable viewing position. 

GSO's rated load capacity for their Crayford focusers is a little less than 6 lbs (2.7 kgs). The focuser also has two large thumbscrews. The thumbscrew on the telescope side can be used to lock the focuser, allowing the use of heavy accessories or cameras without fear or slippage or losing focus. The other thumbscrew on the eyepiece end can be used to adjust the tension of the focuser to achieve a focusing "feel" that you like.  At the easiest (lightest) setting, the focuser moves extremely smoothly. At tighter settings, you can still use heavier accessories without sacrificing much of the smooth focuser action.

Please note that some larger Meade and Celestron SCTs (11" and larger) have a larger 3.25" rear thread, so please make sure that you have an adapter that reduces that larger thread to the smaller 2" SCT thread. If you have a standard 1.25" SCT visual back, all you need to do is unscrew the visual back and screw on the SCT Crayford focuser in its place.  The focuser is shipped in a foam-fitted box. 

Specifications:
• Minimum focuser height (with 1.25" adapter) = 4.29" (109mm)
• Maximum focuser height (with 1.25" adapter) = 5.28" (134mm)
• Minimum focuser height (without 1.25" adapter) = 3.90" (99mm)
• Maximum focuser height (without 1.25" adapter) = 4.88" (124mm)
• Tube travel = 0.99" (25mm)
• Focuser weight (with 1.25" adapter) = 1lb-10.5oz (751gm)
• Focus knob diameter = 1.57" (40mm)
• Microfocus knob diameter = N/A
• Maximum outer barrel diameter = 3.3" (84mm)
-Thread: Standard SCT female thread (2" x 24TPI)
• Millimeter markings on focuser drawtube: Yes
• Rotatable: Yes
• Dust plug: One 1.25" dust plug included 

Please note: Most GSO Crayford focusers have or will soon develop two bearing marks/lines on the upper side of the drawtube. This is caused by wear on the barrel anodizing where is makes contact with the roller bearings. In some focusers, you have to look hard to find these marks. In others, it is very prominent, even for brand new items received from GSO. This does not indicate a defective or used product and is essentially just cosmetic.

* Please also note: Some Celestron telescopes made in the late 1970s and early 1980s did not have a standard thread pitch. This focuser will not fit those, and there is no way for us to know what threads you might have on your telescope.

Reviews

5.0 (Based on 4 Reviews) 100% of reviewers recommended this product.
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    1. Dave P

      Dave P New Member

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      User Notes:
      Review by David P.
      1525311597
      May 2, 2018

      5.0 Great Upgrade

      Pros:

      Cons:

      Comments:

      My 150mm Mak has enough image shift at high powers to be very annoying when focusing. Problem solved with this focuser. I do not do imaging, so I went with the single speed and it is all I need.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    2. Guest

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      User Notes:
      Review by Kevin F.
      1517281813
      Jan 29, 2018

      5.0 Beautiful single speed focuser for

      Pros:

      Cons:

      Comments:

      Beautiful single speed focuser for my 6" Celestron SCT. Particularly useful for focusing with my astrophotography setup. I haven't used for visual but would fully expect excellent performance here as well.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    3. Guest

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      User Notes:
      Review by Avid astronomer of Grass Valley California.
      1454630400
      Feb 4, 2016

      5.0 Simple Crayford focuser

      Pros:

      Easy to Use,Accurate,Strong Construction

      Cons:

      Comments:

      This unit is a quick and easy way to focus CCD equipment as well as a universal way to switch between CCD and and DSLR cameras

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    4. Guest

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      User Notes:
      Review by vsoer of Glen Ellyn, IL.
      1294099200
      Jan 3, 2011

      5.0 GSO Crayford for SCTs

      Pros:

      Compact,Strong Construction,Accurate

      Cons:

      Comments:

      Use with C14. This allows fine focusing, even though it is single speed. You should see Jupiter with it!

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Specifications

      Manufacturer GSO
      Focuser Telescope Type SCT