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GSO 2" Crayford Focuser for Refractors - Single Speed (with 86.4mm Telescope Adapter)
| Brand | GSO |
| Part Number | PAF-GS-CRF-R |
| Availability | available |
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Product Info
Manufacturer Description
This very high quality, single-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
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.
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 an 86.4mm (3.40") base plate adapter.
Click here for a telescope compatibility table to see which focuser might work for you.
Click here to see photos of Crayford focuser installations on various telescopes.
If the basic focuser size (86.4mm) 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 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)
9. Focuser Specifications
• Flange outer diameter on telescope adapter: 86.4mm (3.40")
• Minimum focuser height (with 1.25" adapter and base flange) = 118mm (4.65")
• Maximum focuser height (with 1.25" adapter and base flange) = 197mm (7.76")
• Minimum focuser height (without 1.25" adapter but with base flange) = 108mm (4.25")
• Maximum focuser height (without 1.25" adapter but with base flange) = 187mm (7.36")
• Tube travel = 79mm (3.11")
• Focuser weight (with 1.25" adapter) = 1lb-11.0oz (765gm)
• Focus knob diameter = 40mm (1.57")
• Microfocus knob diameter = N/A
• Laser-etched scale markings on focuser drawtube: Yes
• Rotatable: Yes
• Dust plug: One 1.25" dust plug included
Specifications are subject to change without notice. Please verify with us if necessary.
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.
Reviews
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May 22, 2019
Celestron 90GT OTA fitment
Pros: Cons: Comments:Fit right in with the original screws. Also easily attached the adapter (sold separately) for my finder scope. Way smoother than the stock focuser. Had my first night of ultimate seeing soon after installation. Able to get great focus at near maximum magnification. (143x on Jupiter, 218x on Saturn) This turned my 90mm OTA into a keeper for me! Now to get a 2" diagonal...
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
May 7, 2019Meade Polaris 90 upgrade.
Pros: Cons: Comments:I Replaced the stock Focuser on my Meade Polaris 90 with this, what an upgrade!!
Bottom Line: Would you recommend this item? Yes
Focusing is 100% better, buttery smooth and it fits perfectly.This review was provided courtesy of AgenaAstro.com
Oct 12, 2018Saved my ST90
Pros: Cons: Comments:I'm so glad I bought this gem. It turned my Orion ST90 into my grab-&-go scope. The stock rack-and-pinion focuser was so bad I almost gave away the scope at one point. I bought this excellent GSO Crayford style focuser and it works beautifully. I almost bought the dual-speed model but this works perfectly. It shipped very quickly and was packed well, double-boxed. Thanks, Agena, for a great product and excellent service.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Jan 7, 2018GSO 2" Single Speed Crayford Refractor Focuser
Pros: Cons: Comments:Very nicely built and finished. Major upgrade, at a very reasonable price, over the rack & pinion focusers that come standard on many refractors. Highly recommended!
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Oct 17, 2017Valuable Upgrade
Pros: Cons: Comments:I replaced the stock 1.25" focuser on my 80mm f/5 refractor with the 2" GSO single speed Crayford. The swap was simple - remove three screws, remove old focuser, insert new focuser, done. Fit was perfect and collimation remained unchanged. Focuser construction is first class and operation is smooth and positive. TFOV with a 30mm 2" eyepiece is over 5 degrees. A finder scope base designed for this focuser is a must. I am super pleased with this product.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
PXR-5 Well-Known Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by Jeffrey P.
Oct 9, 2015GSO Single Speed Crayford Focuser Rocks!
Pros:Quality build,Rotatable,Easy to Use,Easy install,Accurate
Cons:Heavy
Comments:GSO Crayford single speed focuser was an easy drop-in replacement to the stiff and sloppy stock focuser on my Orion ST-80 refractor. What a vast improvement over the original. My only nit is that it skews the balance towards the back end of the scope so I have to compensate the front end weight. Agena's service and delivery was excellent in all aspects.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Oct 9, 2015Excellent choice for upgrade
Pros:Easy to Use,Smooth Accurate And Ve,Lightweight,Strong Construction
Cons: Comments:This was an upgrade for my short tube 80mm refractor. It took my affordable scope to the next level.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Jan 30, 2015Excellent for the Orion ST-80
Pros:Easy to Use,Strong Construction
Cons: Comments:Very good focuser. I used it to replace the Orion ST80 stock focuser. This is a perfect fit. The whole operation took about a minute, you need only a screwdriver. The quality and the finish is excellent. The operation is silky smooth.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Jan 30, 2015First-rate focuser
Pros:Strong Construction,Easy to Use,Accurate
Cons: Comments:I actually have 2 of these. One is on a 5" apogee refractor and the other is on a Meade model 395 refractor. They work well with all my eyepieces regardless of size/weight and the collimation is perfect.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Oct 6, 2014Great Focuser Replacement for ST-80
Pros:Strong Construction,Easy to Use,Accurate,Lightweight
Cons: Comments:Excellent service from Agena Astro. The focuser was shipped on the day of the order and was received quite quickly. This focuser is a perfect fit for Orion ST-80 refractor. It only takes 2 min. and a Philips screwdriver to make the upgrade and the result is worth every penny. It converts the small inexpensive ST-80 into an excellent wide view scope. The focuser is of excellent quality, both in construction and finish. It is extremely smooth and adjustable.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Feb 7, 2014A big improvement over the original
Pros:Accurate,Easy to Use,Strong Construction
Cons: Comments:I installed it on an Orion Short Tube 80 to allow the use of 2" accessories such as focal reducers which it does very well as well as being much more precise than the original focuser.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Jan 25, 2014Direct fit for Orion's ST-80 refractor
Pros:Compact,Strong Construction,Easy to Use,Accurate
Cons: Comments:This focuser is a perfect replacement for the stock rack-and-pinion focuser that comes on the Orion ST-80 compact refractor. I replaced mine with this one and it is rock solid, and doesn't move a bit even with my heavy Canon DSLR and other gear hanging off of the back end of it. The focusing scale is a nice touch, and the adjustable tension makes focusing a breeze. The focuser lock does its job very well also. Fit and finish is perfect, even on the interior. Only tool I required to change the one out on my ST-80 was a Phillips screwdriver. I did end up buying a dovetail mount for my finder, because the ST-80's stock focuser had one built in and this one did not. However, this GSO unit is pre-drilled for one and the one sold by Agena is a perfect fit. I could not think of a single improvement I would make to this focuser, even if I were to make it myself. It will even allow you to add a focusing motor later if you want. Nicely done, well built unit, for sure.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Dec 6, 2013Easy Install, Good Price, Does the Job
Pros:Easy to Use,Well built
Cons: Comments:Excellent upgrade to my ST-80 refractor that will be used as a guide scope. Makes focusing so much nicer. Quick, no hassle installation, with a perfect fit.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
spongebob New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by Spongebob of New Jersey.
Nov 30, 2012SOLID
Pros:Easy to Use,Accurate,Strong Construction
Cons:Heavy
Comments:This was a good direct fit into my ST-80. Its solid and heavy. It's quite good for a single speed, but next time I'll save for a 11:1. Its so much more accurate than the standard R&P focusers.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Sep 21, 2012Great upgrade for ST-80
Pros:Strong Construction,Accurate,Easy to Use
Cons:Needs Initial Adjustment,No instructions included
Comments:Replaces the flimsy stock 1.25" focuser. Much sturdier, & allows the use of 2" diagonals & eyepieces. Even without instructions, I was able to install it & adjust it in 10 minutes. It looks good & it works perfectly.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Feb 24, 2012Well made and smooth in operation
Pros:Accurate,Strong Construction
Cons: Comments:I purchased the GSO to upgrade an old Orion refractor that had a very poor focusser. I knew that it would not be an exact match, but with a little work I was able mate this nice quality unit and substantially improve the utility of my refractor - making it a much better guidescope. The focus lock is solid and the graguations allow me to prefocus my guide camera very close to final focus. This saves time and I no longer worry about the camera's position shifting during an exposure. And the price was very good for such a quality accessory.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
AstroGuy1 New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by link of Preston, Lancahire, UK.
Dec 26, 2011Crayford focuser
Pros:Delighted by the quality,Easy to Use,Accurate,Compact,Strong Construction,Lightweight
Cons: Comments:I did not understand the use of the word - buttery- thought it was a silly non engineering term. But yes the feeling is both buttery and precise. All telescopes should have a focus mount like this one, I am absolutely delighted, and it was well worth ordering it from America.
Bottom Line: Would you recommend this item? NoThis review was provided courtesy of AgenaAstro.com
Oct 31, 2011Strong focuser, ideal for a ATM refractor
Pros:Strong Construction,Accurate
Cons: Comments:If one wants to build a quality refractor, just add a tube and a 80 mm lens and here you go!
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Jul 29, 2011GSO single speed focuser with Orion ST80
Pros:Strong Construction,A pleasure to use,Perfect Fit,Excellent quality
Cons:None really
Comments:I purchased the GSO single speed focuser as a replacement for my Orion ST80; it arrived from Agena well-packed and lightning fast.
Bottom Line: Would you recommend this item? Yes
This is a drop-in replacement for the stock focuser: the screw holes lined up absolutely PERFECT and the stock screws were exactly correct for the new focuser. Absolutely nothing had to be forced, tweaked, or fudged.
There are 4 hex head set screws (requires 2mm wrench) that allow you to rotate the focuser to the desired position for your particular mount.
Fit and finish of this focuser is excellent (like every other GSO piece of equipment I have ever owned). I do not currently have a 2" diagonal, but with a 1.25" diagonal and a (heavy) 40mm eyepiece there is no play or wiggle whatsoever. Focus is very smooth, no tight or loose spots.
My 8" Dob came with a GSO dual speed focuser and I noticed that it was so smooth and precise I seldom use the fine focus knob. Therefore when it was time to upgrade the Orion, I opted for the single speed because I am on a budget and would rather spend the savings on another EP (besides, it can always be upgraded to a dual speed at a later date).
The product description indicates you may loose some outward focus travel; I am happy to say that with the ST80 I gained about 4mm out-focus and about 9mm in-focus (with the 1.25 adapter in place; without the adapter you would loose only 1 or 2 mm of outward travel). In other words, I have more focus travel than the stock unit, which means I can use every combination of diagonal (mirror or prism), eyepiece, or barlow and reach focus every time, no adapter needed.
The ST80 always was a decent performer at low powers, but the sloppy stock focuser could be frustrating and made it feel like a toy. Now it feels (and looks) like a precision instrument.This review was provided courtesy of AgenaAstro.com
Jun 3, 2011Quality item at a good price
Pros:Strong Construction,Accurate
Cons: Comments:I used this to replace the cheap plastic focuser on a Meade 2090 refractor.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Apr 17, 2011A good refractor focuser to upgrade
Pros:Accurate,Stable up to 5 pounds,Good value
Cons:Little bearing,No microfocus
Comments:I have upgraded the original rack&pinion focuser from 80/910 achromat with this item and have not regretted the purchase. The focusing is functionaly and stable with my long sun-prominence-filter-assembly (~3 pounds).
Bottom Line: Would you recommend this item? NoThis review was provided courtesy of AgenaAstro.com
Jan 2, 2011Great Upgrade from Stock Focuser
Pros:Accurate,Strong Construction,Smooth,Stable,Easy install
Cons:None
Comments:Upgrading my Orion 80ST focuser with the GSO was easy, and took about 15 mins. The GSO provides what I need: fast and accurate focusing, 2" and 1.25" eyepiece capability, and strength to hold a heavy 2" Powermate, field flattner and camera without flexing. Agena's scope compatibility chart.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Dec 19, 2010Quality 2" refractor focuser
Pros:Stable drawtube movement,Quality Construction,Perfect Fit
Cons: Comments:Can't ask for a better replacement focuser for the generally poor quality focusers that come with budget refractors.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Apr 30, 2010Way Better than a R & P focuser
Pros:Beautifully Finished,Accurate,Strong Construction,Smooth
Cons:Non-Rotateable
Comments:This is a pretty well made piece of gear. The only drawback is that it is not rotateable, but at the price, it's a high-end improvement for an ST80 or similar rack & pinion type scope.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
cellman New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by Cellman of Texas.
Feb 11, 2010I'm convinced and happy
Pros:Smooth as silk,Strong Construction,Accurate
Cons: Comments:I purchased this focuser as a replacement fo the stock rack and pinion focuser supplied with my 5" refractor. I was sceptical of the price in comparison to many of the other "name brand" products. I must admit, this focuser has satisfied my needs as a visual astronomer as well as it's sturdiness when used to support the weight of my astrophotography equipment. I rate this focuser A+ for those that want high quality at a fair price.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
atelierbks New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by atelierbks of Santa Fe, NM.
Jan 18, 2010Mediocre product
Pros:Attractive to look at
Cons: Comments:The fore & aft roller bearings are spaced too close together, resulting in tube shift with even moderately heavy eyepieces. This induces noticeable off-axis coma toward the bottom (gravity) side of the field. The shift can be eliminated by cranking down on the tension screw but this makes focusing on low f-ratio scopes difficult at powers above 25x per aperture inch. On the other hand, it was only [$]. Given the price, it is a good product for visual observing despite the tube wobble. Astrophotographers will have problems achieving and maintaining accurate full-field focus.
Bottom Line: Would you recommend this item? NoThis review was provided courtesy of AgenaAstro.com
Dec 13, 2009Excellent
Pros:Strong Construction
Cons: Comments:If you are an ETX-70 owner and want to use the ETX on an eq-mount you'll love as it will allow you to upgrade the ETX to a 'normal' focuser. Remove all mounting rings from the focuser and it will slide right in to the back of the metal ETX tube! It all takes minimal effort!
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Nov 10, 2009Good product
Pros:Good Price,Sturdy,Good build quality,Smooth,Good tension control
Cons:Slight image shift
Comments:I purchased this focuser to upgrade my Celestron C80ED. The focuser attached very easily using the specially made Agena Astro attachment adapter ring, and transformed the C80 into a new 'scope! The action is very smooth, and the adjustable tension is great. It's possible to have it set to support heavy diagonals and eyepieces (2" diagonal and Pentax XW30 for example) at zenith without slipping. However, when adjusting the tension knob while looking through the eyepiece, it is possible to detect some image shift as the knob increases its pressure on the underside of the drawtube. This can be lived with though for visual use and the other improvements over the standard rack and pinion focuser make it a worthwhile investment.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Nov 8, 2009Nice focuser.
Pros:Accurate,Strong Construction
Cons: Comments:I used this focuser to replace the stock one that came on my Celestron 80ED scope. The focuser is nice and smooth to use with no backlash.
Bottom Line: Would you recommend this item? Yes
Very nice focuser for the money.This review was provided courtesy of AgenaAstro.com
Jun 3, 2009The GSO Single Speed Focuser is a Winner
Pros:Accurate,Smooth Operation,Light weight,Strong Construction
Cons:No Internal Flocking
Comments:The GSO Single Speed Crayford Focuser is a time tested unit that has been an asset to the budget minded amateur astronomer. Over the past few years, I have loved using it for visual as well as for astrophotography. The graduated focuser tube aids in precise focusing when imaging.
Bottom Line: Would you recommend this item? Yes
Its beautiful appearance, all aluminum construction, and stainless steel ball bearing tracking really make this focuser a smooth operator.
The only issue I have found with this focuser is the lack of flocking. But, this can be solved in a couple of ways with ease.
It is definitely a keeper.This review was provided courtesy of AgenaAstro.com
davesnothere New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by Hillcrest Observatory of Live Oak, Florida.
May 26, 2009Butter smooth Yet strong
Pros:Strong Construction
Cons: Comments:Smooth operation yet strong enough to not slip when using heavy eyepieces or doing astrophotography with my D80 DSLR. I like the brass compression rings. There is no image shift when focusing. I put this on a Home built 105mm f/13 refractor with a tube adaptor. My only regret is that I sold the scope with the focuser on it.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
May 26, 2009Single Speed focuser
Pros:Strong Construction,Compact,Smooth function
Cons:None
Comments:I've used the focuser on my 90mm shorttube Orion telescope as a replacement for the old rack and pinion synta OEM focuser and it works like a champ. You really don't need the dual speed because the focuser is so smooth. Its fit and finish are also top quality.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
AstroGuy1 New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by cosmic109 of Georgia.
Feb 2, 2009Staying Focused
Pros:Well built,Accepts 2-inch eyepieces,Focus action very smooth,Brass compression rings
Cons:Not rotatable
Comments:Everyone knows how popular Orion's ST80 f/5 refractor is among amateur astronomers, but to me one of its major weaknesses is the focuser. Too much slop, and a sticky rack and pinion. My solution to this problem was to acquire a GSO single speed, non-rotatable, 2" Crayford focuser from Agena AstroProduts for about $100.
Bottom Line: Would you recommend this item? Yes
The focuser is solid as a rock, and the focus action is as smooth as silk! The unit comes with a 86mm adapter that mounts to the ST80's tube without any modifications, and uses the three screws that are part of the scope's old focuser. I can't describe how delighted I am with this setup. This simple modification truly lets the ST80 strut its stuff! Now, I'm also able to use several of my 2" wide angle eyepieces, and believe it or not.....a Burgess Binoviewer with no problems. There is also a provision to mount a finder dovetail plate to either side of the focuser.
This unit is well built and worth every penny. When it comes to transforming a marginal small 80mm f/5 scope into a great performer, this crayford focuser stays focused on the task at hand. Highly recommended!This review was provided courtesy of AgenaAstro.com
melonman New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by melonman of Minnesota.
Nov 18, 2008GSO Crayford style single speed focuser
Pros:Smooth even movement
Cons:Not for very heavy EPs,Little tight on some EPs
Comments:When I built my 10 inch dobsonian reflector I put in a 2 inch to 1.25 inch rack and pinion focuser. Problem was that the 1.25 adapter was too loose. Also, the eye pieces changed direction a small amount while racking in and out. This caused collimation problems because the Laser and Chesire tools wobbled as well. When I bought the GSO focuser I noticed it was as low a profile as my first (about 3 inches high) and lighter in weight (aluminum). I installed it first trying the same screw holes. Yes they were the same but I moved it a little anyway after realizing I could get my collimation better. Collimation (no wobble) Laser beam comes back into target in my GSO laser like a single beam..... bulls eye! (same with chesire sight tube).
Bottom Line: Would you recommend this item? Yes
Trial: Eyepieces fit very tight but some are hard to push in. Focuser can be pushed or pulled in or out while adding or removing eyepieces but easily holds my heaviest Superview eyepiece up. I learned to have a tight set screw while changing eyepieces. Another difference, adjustment knobs spin free until the set screw is released. So far, I am very pleased.This review was provided courtesy of AgenaAstro.com
Nov 12, 2008Best value in a single-speed crayford
Pros:Strong Construction,Accurate
Cons: Comments:I currently own two of these focusers, one is the previous model and one is the current version with the new black draw-tube and numerical focusing scale. I think any ATM who's looking for a refractor crayford would be hard pressed to find better value in terms of quality, fit and finish, and stability.
Bottom Line: Would you recommend this item? Yes
My older GSO single-speed is installed on a self-built 80mm F5 refractor which is used primarily as a guidescope. It is mounted to a 4" OD hastings tube using a custom aluminum spacer ring that I machined on a small lathe. Thus far I have not experienced any flexure whatsoever with this focuser. My newer version is attached to an Orion 80ED and is often used to hold my QHY8 camera plus a Paracorr. Again, zero flexure that I can detect during my measurements.
Overall these focusers are good performers for astrophotography and are more than adequate for visual observing. The action is smooth and a joy to use. The look of these focusers, while somehwat subjective, I think is very attractive and will universally go with just about any color scheme you are cooking up.
The only thing that might qualify as a conideration is the dual locking bolts on the bottom of the flange. It takes some experimentation to figure out how to properly use them, but once you get it it's very easy to make adjustments from that point forward, even while not looking at them in the dark.
I plan on purchasing a third one in the very near future for another longer FL guidescope I am planning.This review was provided courtesy of AgenaAstro.com
Mar 15, 2008GSO Focuser
Pros:Well built; Adjustable for collimation; Good Price; Great value
Cons:??????? I've got nothing
Comments:I built a 105mm f/13 refractor and used the single speed GSO focuser. I had concerns due to the economical price but I could not afford a high dollar version.
Bottom Line: Would you recommend this item? Yes
When I received the focuser I could tell it was well built at first sight. It installed with ease and made collimation easy as well. I was still concerned with its ability to focus and hold a heavy EP or my Fujifilm S1 pro DSLR... NOT A PROBLEM - just snug up the tension screw. And butter smooth focus even with the DSLR when the scope was pointed at the zenith.
I chose this focuser due to its cost and feared low quality. Usually you get what you pay for. But that's not true in this case. You get more than you pay for.Mar 3, 2008Staying Focused
Pros:Well built; Accepts 2" eyepieces and accessories; Brass compression rings; Focus action very smooth.
Cons:Non-rotatable.
Comments:Everyone knows how popular Orion's ST80 f/5 refractor is among amateur astronomers, but to me one of its major weaknesses is the focuser. Too much slop, and a sticky rack and pinion. My solution to this problem was to acquire a GSO single speed, non-rotatable, 2" Crayford focuser from Agena AstroProduts for about $100.
Bottom Line: Would you recommend this item? Yes
The focuser is solid as a rock, and the focus action is as smooth as silk! The unit comes with a 86mm adapter that mounts to the ST80's tube without any modifications, and uses the three screws that are part of the scope's old focuser. I can't describe how delighted I am with this setup. This simple modification truly lets the ST80 strut its stuff! Now, I'm also able to use several of my 2" wide angle eyepieces, and believe it or not.....a Burgess Binoviewer with no problems. There is also a provision to mount a finder dovetail plate to either side of the focuser.
This unit is well built and worth every penny. When it comes to transforming a marginal small 80mm f/5 scope into a great performer, this crayford focuser stays focused on the task at hand. Highly recommended!Dec 28, 2006The GSO Crayford style single speed Focuser.
Pros:Smooth even movement and all sizes of eyepieces are held firmly.
Cons:Maybe a little tight on some eyepieces, possible trouble with very heavy eyepiece.
Comments:When I built my 10 inch dobsonian reflector I put in a 2 inch to 1.25 inch rack and pinion focuser. Problem was. the 1.25 adapter was too loose. Also, the eye pieces changed direction a small amount while racking in and out. This caused collimation problems because the Laser and Chesire tools wobbled as well. When I bought the GSO focuser I noticed it was as low a profile as my first (about 3 inches high)and lighter in weight (aluminum). I installed it first trying the same screw holes. Yes they were the same but I moved it a little anyway after realizing I could get my collimation better. Collimation (no wobble) Laser beam comes back into target in my GSO laser like a single beam..... bulls eye! (same with chesire sight tube). Trial: Eyepieces fit very tight but some are hard to push in. Focuser can be pushed or pulled in or out while adding or removing eyepieces but easily holds my heaviest Superview eyepiece up. I learned to have a tight set screw while changing eyepieces. Another difference, adjustment knobs spin free until the set screw is released. So far, I am very pleased.
Bottom Line: Would you recommend this item? YesSort bySpecifications
Manufacturer GSO Focuser Telescope Type Refractor
