Please note: GSO has modified this model slightly, and the latest version of this item cannot accept dovetail bases for finders as previous versions or some other sizes can. The overall body length of this new version is also a bit (8mm) shorter than before. Also, the rotation collar may be silver (as shown in the photos) or black depending on stock.
This very high quality, dual-speed Crayford focuser for refractor telescopes from Guan Sheng Optical (GSO) is beautifully machined and a joy to use. You will wonder how you ever lived without it once you install it!
1. Smooth Focusing Action
The Crayford style focusing control makes 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.
2. High-Quality Construction and Features
CNC machined from aluminum and anodized black, this focuser comes with a base plate adapter to attach to refractor telescopes. The inner drawtube glides on 4 precision bearings and a roller shaft and provides 79mm (3.11") of focus travel. 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 inner draw-tube barrel is anodized black and features a laser-etched scale.
3. Tension Adjustment and Focus-Lock
The focuser has two large thumbscrews on the underside. 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 about 6 lbs (2.7 kgs).
4. 360-degree Rotation
This focuser model features a large black (not silver as shown above) rotation collar which makes it a breeze to rotate the focuser in the desired orientation for maximum comfort. Note that the silver rotation thumbscrew in the photo above is not applicable to this focuser and is often not included.
5. Focuser Installation
The focuser is easily attached to a telescope tube with three M4 screws (not included) spaced 120 degrees apart on the flange. Installation is usually a 5 minute job that involves removing your old focuser, sliding in the new Crayford focuser, and screwing it on to the telescope tube. In almost all cases, the original screws used on your OEM focuser will also work for this Crayford focuser. If not, you will have to buy the M4 screws from a local hardware store. You will just need a Philips (cross-slot) screw-driver to perform this upgrade.
We strongly recommend that you make sure that you can remove your old focuser from your telescope tube before buying this item. Some OEM R&P focusers can be very hard to remove.
6. Selecting a Focuser Model for your Telescope
The focuser comes with a 112.5mm (4.43”) base plate adapter.
If this focuser flange size (112.5mm) does not fit your telescope, we also sell some other adapters that can be used to connect this focuser to several telescope models from Antares, Meade, Celestron, and others. Adapters for the popular Celestron 80ED and 100ED refractors are also available.
7. Focus Travel Issues
Most Crayford focuser units are shorter than existing R&P focusers. So while you will typically have more in-focus travel with a new Crayford focuser (which is great for imaging applications), you might not have sufficient out-focus travel to reach focus with all your eyepieces/accessories. In such cases, the problem can be easily fixed with 2" extension tubes that are available separately.
8. Optional Finder Mounting Options
In many existing focusers, the base for your finder bracket is molded onto the focuser body. When you replace the existing focuser with a Crayford focuser, you will lose this base to mount your finder.
This new version of the GSO focuser has three finder mounting screws on the upper left side of the body and one finder mounting screw on the upper right side of the body. Unfortunately, you can no longer attach conventional Synta-style dovetail bases as in previous versions. However, using one of these holes, you can mount the following finder bases/bracket which is sold separately:
- GSO 50mm finder bracket with base # 8KB01 using one screw (on left or right side)
9. Focuser Specifications
• Flange outer diameter on telescope adapter: 112.5mm (4.43”)
• Minimum focuser height (with 1.25" adapter and base flange) = 147mm (5.79”)
• Maximum focuser height (with 1.25" adapter and base flange) = 226mm (8.90”)
• Minimum focuser height (without 1.25" adapter but with base flange) = 137mm (5.39”)
• Maximum focuser height (without 1.25" adapter but with base flange) = 216mm (8.50”)
• Tube travel = 79mm (3.11")
• Focuser weight (with 1.25" adapter) = 2lb-10.2oz (1196gm)
• Focus knob diameter = 40mm (1.57")
• Microfocus knob diameter = 26mm (1.02”)
• Laser-etched scale markings on focuser drawtube: Yes
• Rotatable: Yes (using silver/black collar)
• 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.
Apr 10, 2019
Works great!Pros: Cons: Comments:
Fit my Orion 120mm f/8 refractor (version collimatable objective.) Way smoother action and sturdier than the stock r&p focuser. Did require an extension tube but im using an old Barlow with the cell removed until I order a 2 inch extension tube.
This review was provided courtesy of AgenaAstro.com
Tank New Member
- Skill Level
- Time with Product
Sep 26, 2017
- User Notes:
- Review by Tony M.
GSO focuserPros: Cons: Comments:
Smoother than i thought it would be
I own FT and Moonlite and really like this one also
One thing i wish they have more adapter flange sizes i think if they did these would sell alot more!
This review was provided courtesy of AgenaAstro.comJan 6, 2017
GSO Focuser for RefractorsPros: Cons: Comments:
I love this new focuser. I had to get it turned down a few milometers and I corrected the culmination easily. I use it on my CGEM and it works beautifully. Thank you Agena for sticking with me on the purchase procedure on this item.
This review was provided courtesy of AgenaAstro.comSep 30, 2016
Somewhat Short TubeComments:
This was purchased as an upgrade from the focuser that came with a 120mm f/8.3 optical tube. The image quality improved dramatically with the collimation being held more reliably; this was purchased with an adapter flange. Both parts were easy to install as a direct replacement for the stock focuser assembly, using the original screws. I find that use across a wide range of subject distances more often requires extensions, as it has about half the travel of my original unit, but it's still overall a worthy replacement for the original rack and pinion unit.
This review was provided courtesy of AgenaAstro.comDec 6, 2013
GSO Crayford Focuser ReviewPros:
Strong Construction,Smooth,Fine Touch Feel,Accurate,Lightweight,Precise,Easy to UseCons: Comments:
Select the right size for your telescope. Installs easily. A dream to use. Saves a lot of time in getting correct focus for visual or astrophotography.
This review was provided courtesy of AgenaAstro.com
Lowjiber New Member
- Skill Level
- Time with Product
Oct 24, 2013
- User Notes:
- Review by John aka "Lowjiber" of Las Vegas, Nevada.
On Celestron OMNI 120mm refractorPros:
Quality Lenses,Accurate,Strong Construction,Easy to Use,CompactCons:
Added 50mm BackfocusComments:
This is a great value and a quality product. I cannot believe how smoothly it operates. I have another brand of Crayford two-speed focuser on my Dob that is nowhere as smooth or solid-feeling as this GSO.
Installation was about as simple as it gets. Remove the three screws holding the OEM focuser and slide this baby in place with the original screws.
This focuser does not have quite as much travel as the OEM focuser, so I added a 55mm back-focus extender to accommodate a camera that I use on occasion. If you're only using the usual range of eyepieces, you won't need an extender.
I also added a GSO dielectric diagonal to finish a really nice upgrade to the scope.
You'll loose your finder scope dovetail mount that is built into the OEM focuser. I added the "modified" finder adapter found on this website. Again, a simple one-screw installation now holds my RACI 9x50 finder scope.
This review was provided courtesy of AgenaAstro.comJul 29, 2013
Strong Construction,Easy to Use,AccurateCons: Comments:
Leaps and bounds over the original focuser for my omni xlt120. The bottom locks took a little while to figure out, less than 10 minutes really. My brain was on vacation I guess. Now, no loss of focus with my heavy eyepieces or camera. I'm actually going to order one for my 150mm next. That's how good they are, and shipping to Chicago was faster than most places IN Illinois.
This review was provided courtesy of AgenaAstro.comJul 2, 2012
A nice upgrade with a little helpPros:
Accurate,Easy to Use,Strong ConstructionCons: Comments:
Just purchased the 112mm GSO Crayford focuser for my Celestron C6R-GT. It should have taken the 96mm one but I wanted the rotating ring featured on the 112. I had a local machine shop turn about 3-4 mm from the inside of the adapter housing and it fit perfectly! Very smooth operation and solid construction. I like the etched scale on the drawtube so I can now start recording best focus points and different ranges for my eyepieces. The rotating setup makes taking pictures much easier.
This review was provided courtesy of AgenaAstro.comNov 7, 2011
Great replacement focuserPros:
I bought this GSO focuser as a drop-in replacement for my Orion 120ST. I already had an Orion Crayford Style focuser in that scope but I wanted to move that focuser to the long tube Orion 120 I just bought (to replace the R-n-P focuser) and not replace the Orion focuser with another Orion focuser. As advertised by Agena, the swap was as simple as removing the three screws, swapping out the focusers and replacing the screws. The GSO focuser fit is a skosh looser than the Orion focuser but that's not a problem. Since I'm rather new to Crayfords (only a few months now), I'm still on the "honeymoon" with them versus rack and pinion. Crayfords really are the way to go and I especially like the rotatable feature of the GSO. I also purchased the "Synta-style" dovetail mount for my finder scope and installing that was as simple as removing one of the set screws and installing the mount on the GSO with the included screw.
This review was provided courtesy of AgenaAstro.comAug 20, 2009
Strong Construction,Nice Finish,Makes focusing a pleasureCons: Comments:
I now enjoy focusing my telescope!so much better than anything i've used before. And this isn't just for planetary observers. Try focusing on the sword handle in Perseus & tweaking the fine focus to see how many more faint stars you can see! Great product,any cons? Well the drawtube is beautifully rifled inside and anodised black, just a little shiny for my liking, easily remedied with some matt black paint, & this is a minor point.
This review was provided courtesy of AgenaAstro.comSort by
Manufacturer GSO Focuser Telescope Type Refractor