This very high quality, dual-speed Crayford focuser for reflector telescopes from Guan Sheng Optical (GSO) is a joy to use. You will wonder how you ever lived without it once you install it! It will make achieving precise focus for visual observations and astrophotography a breeze and you will experience very smooth and precisely controlled focuser motion with zero backlash and zero image shift.
This is a "Low Profile" model that is shorter than the regular model, yet it provides 39mm of focus travel. This is ideal for telescopes requiring more in-focus travel for visual/imaging applications as compared to the regular model.
CNC machined from aluminum and anodized black with a chrome-plated inner barrel, this focuser comes with a base plate to attach to your reflector telescope. 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.
The 2" focuser barrel features a brass compression ring so your eyepieces and other accessories will not be marred by the set-screw. Also included is a 1.25"-2" adapter with brass compression rings that is threaded to accept standard 2" filters.
The focuser comes with a curved base plate (available in 8"/10" and 12" models) for mounting on many telescopes. Please make your size selection while ordering this item. Flat bases are also available at an additional charge. For help in deciding which base plate to choose (including specifications and hole spacing), please click here.
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. GSO's rated load capacity for their Crayford focusers is a little less than 6 lbs (2.7 kgs).
Focuser Specifications (With 8"/10" Base Plate):
- Minimum focuser height (with 1.25" adapter) = 2.44" (62mm)
- Maximum focuser height (with 1.25" adapter) = 3.98" (101mm)
- Minimum focuser height (without 1.25" adapter) = 2.05" (52mm)
- Maximum focuser height (without 1.25" adapter) = 3.58" (91mm)
- Tube travel = 1.54" (39mm)
- Focuser weight (with 1.25" adapter) = 1lb-4.9oz (592gm)
- Focus knob diameter = 1.26" (32mm)
- Microfocus knob diameter = 1.02" (26mm)
- Maximum outer barrel diameter = 3.15" (80mm)
- Millimeter markings on focuser drawtube: No
- Rotatable: No (But body can be rotated by loosening two allen screws that connect the focuser to the base plate)
- 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.
- User Manual: Optimizing the Performance of your GSO Crayford Focuser