This GSO Dual-Speed Linear Focuser for refractor telescopes features the most recent innovation in focuser design to hit the astronomy market in recent years. It is designed specifically to meet the heavier equipment and stability requirements of astrophotography equipment and heavy eyepieces. The linear stability and repeatable quality of focus reached with this focuser will have you returning night after night for more spectacular views, sharper images, and consistent enjoyment!
Eliminate Focuser Drawtube Slop
In conventional Crayford focusers, the drawtube is held in place by four roller bearings. Because of the small area of contact between the focuser tube and these bearings, changes in load or telescope orientation can cause some amount of slop in the focuser drawtube. The new linear bearing focuser is built with a cutting-edge rail system made of stainless steel which provides extended, consistent, and linear contact with the focusing mechanism and the inside of the focuser body, even when the focuser is fully extended. The result is zero flexure throughout the focus travel range, even in the worst case scenario when the focuser is parallel to the ground and carrying a heavy load such as a large CCD camera. This linear bearing rail mechanism also allows the use of heavier loads (GSO's rated load capacity for their linear bearing focusers is about 9 lbs (4.1 kgs)).
Smooth Focusing Action
The ultra-smooth focuser adjustment knob is only topped by the 10:1 fine adjustment knob which yields superior fine-tuning that will stay in place without slippage for hours on end. You'll feel as if the focuser is gliding on air as you meticulously seek the perfect focus. For critical imaging applications, the focuser position can be locked in place via the large thumbscrew provided for this purpose on the top of the focuser. The focusing tension can be controlled by another large screw on the underside of the focuser. The drawtube features a laser-etched measurement scale for quick and repeatable focusing.
Very High Quality Construction and Features
The highly polished, anodized black aluminum is complemented by the meticulous CNC machining. Every part is carefully selected and designed to deliver a linear focusing system that will provide both beauty and quality for years to come. The 2" focuser barrel features a brass compression ring. Also included is a 2"-1.25" adapter with brass compression rings and threads to accept standard 2" filters. The focus travel is 2".
These focusers are rotatable, i.e., you can turn the entire focuser body/diagonal/eyepiece combination into a better observing position by loosening or tightening a large silver thumbscrew on the top of the focuser. However, please note that this is a relatively weak feature of this otherwise excellent product. We inspect every single focuser and tweak/lube it as much as we can, but the rotation is often not smooth over the entire 360-degrees and may bind in a few spots, requiring additional effort to rotate it. This is probably a minor annoyance since most people will not use this feature very often.
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.
Selecting a Focuser Model for your Telescope
The focuser comes with a 96.6mm (3.80") base plate adapter.
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.
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 version of the GSO focuser has one finder mounting screw on the upper left side of the body and one finder mounting screw on the upper right side of the body. Using one of these holes, you can mount the following finder bases/brackets, all of which are sold separately:
1) Agena modified Synta/Vixen style dovetail base for Crayford focusers # CFURB using one screw (on left or right side)
2) Agena Synta/Vixen style deluxe cross-slot dovetail base # XFURB using one screw (on left or right side)
3) GSO 50mm finder bracket with base # 8KB01 using one screw (on left or right side)
• Base flange diameter = 3.80" (96.6mm)
• Minimum focuser height (without 1.25" adapter; including flange) = 4.3" (109mm)
• Maximum focuser height (without 1.25" adapter; including flange) = 6.3" (160mm)
• 2"-1.25" adapter height = 0.39" (10mm)
• Flange length (most or all of which inserts into telescope tube) = 0.59" (15mm)
• Tube travel = 2" (50.8mm)
• Drawtube outside diameter = 2.32" (59mm)
• Steel rail width = 0.56" (14.1mm)
• Focuser weight (with 1.25" adapter) = 1lb-14.6oz (867gm)
• Focus knob diameter = 1.57" (40mm)
• Microfocus knob diameter = 1.06" (27mm)
• Maximum outer body diameter = 3.23" (82mm)
• Measurement scale on focuser drawtube: Yes
• Rotatable: Yes, but see description above
• Dust plug: One 1.25" dust plug included
• The focuser is shipped in a foam-fitted padded box.
• No instruction manual is included.
Dick Gentry New Member
- Skill Level
- Time with Product
Jul 23, 2019
- User Notes:
- Review by Dick G.
met the specs exactly!Pros: Cons: Comments:
The important part of this purchase was that the focuser provide increased back focus for NV use with an ST120 and the focuser, by matching the dimensions in Agena's description, did that very well.
This review was provided courtesy of AgenaAstro.comMay 3, 2019
Excellent ValuePros: Cons: Comments:
It's not a feathertouch, but for the price, this focuser may be unbeatable.
I used it to replace the stock 2-speed crayford focuser on my SW ED100. It's well machined, evenly anodized, and very smooth right out of the box. No disassembly/regrease needed for my copy. It was a simple press-fit and with the stock drilled holes in the ED100 tube. I was able to re-use the same screws- they fit perfectly.
If I had to be nit-picky, I'd say that the internal reflections could be further suppressed by flatter black paint that the variety used in my copy.
Agena shipped the same day I ordered, and I received my order within 2 days. Amazing!
This review was provided courtesy of AgenaAstro.comJan 11, 2018
Very nice!Pros: Cons: Comments:
Product is as advertised. Well made and smooth. Draw tube could be longer but for the money you cant have everything. Agena is awsome to deal with. No hassles and delivery is prompt. Would definitly recommend
This review was provided courtesy of AgenaAstro.com
Lowjiber New Member
- Skill Level
- Time with Product
Dec 16, 2017
- User Notes:
- Review by John C.
Solid and SmoothPros: Cons: Comments:
I have several scopes with GSO focusers and have always been happy with their quality and performance.
I bought this linear bearing model for a SW Pro 1000ED that is teamed with a Quark-C for solar imaging. It's everything I expected. It picks up a four pound load on the back end like it isn't even there.
This review was provided courtesy of AgenaAstro.comJul 11, 2017
Fine Focuser Falls Slightly ShortPros: Cons: Comments:
I own an Orion ED100 and i always knew I would someday upgrade the focuser and that someday is now. I purchased the GSO 2" Linear Bearing Crayford Focuser for Refractors - Dual Speed (with 96.6mm Flange) and I love the fit and finish - very well made. Replacing my old focuser was as easy as 1-2-3 screws. My first clue that I might have problems was when, after replacing the focuser, I went to put it back into my custom OTA carry case and saw that my scope was now a full inch shorter than before. A few days later I mounted up the scope and realized I could not achieve focus with any of my eyepieces. I ordered a 1" extension tube that solved that problem. I also found that I can no longer get focus with my Canon DSLR attached via T-ring/adapter. The third problem is I had to buy a separete dovetail base to attach my finder-scope because the old Orion focuser had the base built onto the focuser assembly. These are minor fixable problems but enough for a one star deduction.
This review was provided courtesy of AgenaAstro.comMar 1, 2016
Big improvement over stock.Pros:
Smooth And Precise,Easy to Use,Strong ConstructionCons: Comments:
Robust construction, nice machine work, very smooth and precise. A vast improvement over the stock rack and pinion focuser that came with my Celestron C6R HD 'scope. There are however, two issues I have;
1) Out of the box, I noticed there was a binding in the fine focus knob. The knob itself is installed too tight up against the coarse focus knob. Just loosen the set screw and pull it out a hair. Simple fix, but still.
2) It could use some extra focus tube length, having only 2". This to is an easy fix as I have extension tubes I can use. But I'd rather not.
If not for these issues, I would have given it a five star rating.
This review was provided courtesy of AgenaAstro.com
- Skill Level
- Time with Product
Mar 30, 2015
- User Notes:
- Review by C6R User of OH.
Strong Construction,Easy installationCons:
Deformed Fine Focus KnobComments:
The unit was quickly and easily installed on my Celestron C6R. This focuser is a vast improvement over the stock unit- much more rigid and smooth. If you want to use a heavy 2" diagonal and big eyepieces this is the way to go.
As stated in the compatibility tables you will need a 2" long extension tube for the C6R. The overall focuser travel IS shorter than other Crayfords. With a 2" diagonal and the 2" extender my eyepieces focus at around 70% of the backtravel.
One fault - the skirt of the fine focus knob was slightly deformed and not running parallel to the face of the coarse focus knob. As adjusted out-of-the-box the two knobs were binding on each other. The focuser was stiff and noisy because of this. By listening to the sound as I slowly turned the knobs I found the problem. Loosening the setscrew and moving the fine knob out about .025" cured it. A simple fix, but the binding was so obvious it should have been found at the factory. I only give the unit 4/5 stars because of this.
For a C6R class telescope this is an expensive upgrade. If you like your scope, however, it is well worth it.
This review was provided courtesy of AgenaAstro.comDec 3, 2013
Great replacement FocuserPros:
Accurate,Easy to Use,Strong Construction,Quality ConstructionCons: Comments:
This focuser was a great replacement for the factory focuser on my Celestron 102GT. The focuser mounted in minutes and is very smooth in operation with 'No' slop. I love the ability to rotated the focuser also.
This review was provided courtesy of AgenaAstro.comNov 29, 2013
GSO 2" Crayford FocuserPros:
Travel Markings,Smooth focusing,No Backlash,Locking Bands,Easy to Use,Strong Construction,Good value,Very Good FinishCons:
This GSO Crayford focuser replaced the stock focuser on my Celestron NexStar 102GT, and the GSO with the 96mm flange fit perfectly. Note: the travel rail on the GSO focuser is shorter than the stock 102GT focuser. I did have to add an adapter so that my Baader Zoom eyepiece could come to focus. And, I had to add a counterweight (DIY from BBs) since the GSO Crayford Focuser and Baader Zoom are somewhat heavy ... but the combination gives great views and is superior to the stock Celestron focuser and eyepieces. The GSO focuser is very smooth and the fine-focus control makes it possible to get pinpoint sharp focus with no backlash.
This review was provided courtesy of AgenaAstro.comOct 1, 2013
GSO 2" Linear Bearing Crayford FocuserPros:
Easy to Use,Strong Construction,AccurateCons: Comments:
I bought a C102GT Refractor and couldn't stand the stock focuser. The GSO was a perfect match for the OTA. The focuser is very smooth in both the regular mode and when using the 10-1 knob.
I did need to ad a 2" extention to get my eyepieces to come to focus. The draw tube is shorter than the stock focuser. Once the adjustment screws on the bottom were set it held even heavy eyepieces with no slippage. I tried a ES 24mm 82
This review was provided courtesy of AgenaAstro.comSep 24, 2012
Strong ConstructionCons: Comments:
This focuser fits my needs perfectly, it is very well constructed, the price cannot be beat, and I like shopping at AGENA ASTRO for lots of my stuff. I am a visual observer,and ALL of my eyepieces are parfocal with each other, so the travel of this focuser is not an issue. Also, these units can be adjusted if you know how to tinker with things like this, so they can perform very well indeed. For the price, the quality, and the performance, I give this a Big 5 rating.
This review was provided courtesy of AgenaAstro.comSep 21, 2012
GSO Linear Beariing Focuser 96mmPros:
Accurate,Strong ConstructionCons: Comments:
A high quality focuser. An easy swap from the R+P, looks great and is nice and smooth, no image shift and focusing is now easy. I would recommend product to any one with R+P focuser. I do have to have a 50mm extension tube to reach focus in my scope, and remove that to use my WO bino's. The rotating part is a bit rough and is one feature I thought I wouldn't really use but I sure was wrong! It's made viewing so much easier. Great value for money. I'm giving it 4 stars ...if the draw tube extended out another 30-50mm it would be 5 stars.
This review was provided courtesy of AgenaAstro.comNov 5, 2011
Strong Construction,Easy to UseCons: Comments:
A great product to enjoy your astronomy nights. It transforms the use of the telescope in a pleasant experience. Perfect for astrophotography.
This review was provided courtesy of AgenaAstro.comJun 29, 2011
Easy to Use,Strong ConstructionCons: Comments:
Lovely replacement focuser for my 6" achro. Doesn't feel as heavy as quoted in the specs but still very sturdy and reliable with heavy diagonal and eyepiece. Quality finish too.
This review was provided courtesy of AgenaAstro.comSort by
Manufacturer GSO Focuser Telescope Type Refractor