Compatibility of GSO Crayford Focusers with Refractor Telescopes

A. Important Information - Please Read

To help select a focuser for your telescope, please refer to the table below. If your telescope is not mentioned in this list, then we do not know which focuser will work for you. In such cases, please contact us with your tube dimensions (exact inner and outer diameter, preferably in mm) and we will work with you to find a solution.

This table is meant to be a general guide and not an authoritative reference. We cannot be responsible for any problems or fit issues. The only way to correctly determine which size focuser/adapter you need is by removing your existing focuser, measuring the inner diameter of your telescope tube, and then making a choice. Before ordering a new focuser, make sure you can remove your stock focuser. Some companies are known to have changed tube sizes and some OEM R&P focusers can be very hard to take off.

B. Focuser Compatibility Information

This table was compiled with the help of numerous Agena customers (Thank you!). If you have any additions, suggestions, or corrections, we'd love to hear from you.

Do you have information on mounting one of these Crayford focusers on a telescope not listed below? Give us complete information for new telescope entries and we will send you a $5 gift coupon!


To make sense of the cryptic abbreviations in the table, see the Key below the table.

Brand
Model
Focuser
Adapter Required?
Focuser Connects To...
Original Screws OK?
Connection Configuration
Focusing Issues *
Comments
Antares 1208/12012 127mm GSO86 Antares J120 Adapter Adapter Yes Focuser Bolts Inside Adapter NR  
Bresser 90mm f/10 GSO86 - Tube ? FBIT ?  
Celestron 80mm f/5 ST GSO86 - Tube Yes FBIT ?  
Celestron NexStar 80 SLT GSO86 - Tube No FBIT ETL C8
Celestron C80ED GSO86 Agena C80ED Adapter Adapter N/A ASOT NR  
Celestron Nexstar 90GT   GSO86 - Tube Yes FBIT NR  
Celestron C100ED GSO86 Agena C100ED Adapter Adapter N/A ASOT ?  
Celestron C4R 102mm f/9.8 GSO96 - Tube Yes FBIT ETL  
Celestron 102mm f/5 GSO96 - Tube Yes FBIT NR  
Celestron 102GT GSO96 - Tube Yes FBIT NR  
Celestron C-102HD 102mm f/10 GSO96 - Tube Yes FBIT ETL  
Celestron Omni XLT 120 GSO112 - Tube Yes FBIT ETD  
Celestron C6R 150mm f/8 GSO96 - Collar on Telescope Tube Yes FBIC ETD  
Discovery 90mm f/5.6 Short Tube GSO86 - Tube Yes FBIT NR  
Konus

KonusMotor 90
90mm f/11

GSO86 - Tube Yes FBIT ?  
Konus Konusky 150mm f/8 GSO86 Antares A150 Adapter Adapter Yes ? ETL  
Meade 90mm f/? GSO86 - Tube Yes FBIT NR C6
Meade Model 390 90mm f/11 GSO86 - Tube Yes FBIT NR  
Meade Infinity 102 AZ GSO96 - Tube Yes FBIT ETD  
Meade AR-5 127mm f/9 GSO86 Antares J120 Adapter Adapter Yes Bolts Outside NR C1
Meade AR-6 GSO86 Antares J150 Adapter Adapter Yes Bolts Outside ? C1
Orion ST80 GSO86 - Tube Yes FBIT NR  
Orion 80ED GSO96 - Tube Probably FBIT NR C2, C4
Orion 80mm f/11.4 OTA GSO86 - Tube Yes FBIT NR  
Orion 90mm f/5.6 Short Tube GSO86 - Tube Yes FBIT NR  
Orion StarBlast 90mm f/6.7 GSO86 - Tube Yes FBIT NR  
Orion 100ED GSO96 - Tube Yes FBIT NR  
Orion Astroview 100mm f/6 GSO96 - Tube Yes FBIT NR  
Orion Astroview 120ST EQ GSO96 or GSO112 - Collar or Tube Yes FBIC or FBIT ETL C9
Orion 120mm f/8.3 GSO112 - Tube Yes FBIT ETM  
Skywatcher 80mm f/5 GSO86 - Tube Yes FBIT ?  
Skywatcher 80ED GSO96 - Tube Yes FBIT ETM  
Skywatcher 100ED GSO96 - Tube Yes FBIT NR  
Skywatcher 102mm f/9.8 GSO96 - Tube Yes FBIT ETL  
Skywatcher 120ED GSO96 - Collar Yes FBIC ?  
Skywatcher (Synta) 120mm f/? GSO96 - Collar Yes FBIC ETL  
Stellarvue AT1010 Classic GSO86 - Tube Yes FBIT NR C1, C3, C7
Stellarvue AT1010 Nighthawk GSO86 - Tube Yes FBIT ETM  
Synta 90mm f/5.6 Short Tube GSO86 - Tube Yes FBIT NR  
Vixen A80Mf GSO86 - Tube ? FBIT NR  
Vixen ED100Sf GSO96 - Tube ? ? ?  

C. Key for Compatibility Table Above

* - 'Focusing Issues' are as measured with a GSO single or standard dual speed focuser with a drawtube travel length of 80mm. If you are considering a GSO linear bearing focuser, then the drawtube is 30mm shorter.

Focuser
GSO86 - GSO Crayford Focuser with 86.4mm Adapter (Single or Dual Speed)
GSO96 - GSO Crayford Focuser with 96.6mm Adapter
GSO112 - GSO Crayford Focuser with 112.6mm Adapter

The William Optics Synta Focuser with 96mm Flange can be used instead of the GSO96 focuser listed above, but the 'Focusing Issues' column data may not apply.

Connection Configuration:
ASOT - Focuser bolts inside adapter; Adapter screws on outside the telescope tube
FBIC - Focuser bolts inside collar already on the telescope tube
FBIT - Focuser bolts directly to inside of telescope tube

Focusing Issues:

ETD - An extension tube is definitely required for additional back-focus travel (need at least a 2" extension on the Celestron C6R).
ETL - It is possible that you might need an extension tube for additional back-focus travel. However, we don't have enough data to state this conclusively.
ETM - Most customers did not need an extension tube, although it is still possible that you might need one.
NR - No extension tube required.

Comments:
C1 - OEM focuser can be hard to remove
C2 - 3 customers had tubes with ID = 96mm and could use the original screws. One customer reported an ID = 97.5mm and needed new screws
C3 - Holes don't line up perfectly, so screws are angled and don't go in all the way
C4 - Customers have reported different tube diameters for different year models
C7 - Customers have reported different tube diameters for different year models; One customer had no problems inserting the GSO Crayford. Another had to machine the flange down by about 1/16" to make it fit inside the AT1010 tube.
C8 - The original screws on this telescope are cheap sheet metal screws and need to be replaced by M4 screws
C9 - GSO96 connects to collar on tube; GSO112 can be connected directly to the tube without the collar