Which telescopes is this Starlight Instruments 2.0" adapter designed for?
This adapter attaches to the 2"-24tpi rear cell thread of Schmidt-Cassegrain and Maksutov-Cassegrain telescopes. It is known to fit the Celestron C8/CPC8 and C9.25/CPC9.25, and the Meade 8" RCX400, 8" LX90 and 8" LX200 SCTs.
I have a Celestron 8" SCT on a fork mount. Will this adapter let me install a 2.0" Feather Touch focuser?
Yes, this adapter is made for exactly that purpose. It will thread onto the 2"-24tpi rear cell of your 8" SCT, providing the correct interface to mount a 2.0" Feather Touch focuser.
Why should I replace my SCT's stock focuser using this Starlight Instruments 2.0" adapter?
The primary reason is to eliminate image shift. Stock SCT focusers move the primary mirror, which can cause the image to shift during focusing. An external focuser like the Feather Touch, mounted via this adapter, provides much finer, more stable control that is critical for high-magnification visual use and astrophotography.
What is the thread size on this Starlight Instruments 2.0" adapter?
This adapter features a female 2.0"-24tpi (threads per inch) thread. It is known as the small SCT thread.
Will this adapter work on a non-fork-mounted Celestron EdgeHD 11"?
Starlight does not list it for that telescope: its known-to-fit list covers the Celestron C8/CPC8 and C9.25/CPC9.25 and the Meade 8" RCX400, LX90 and LX200 only. Starlight Instruments offers a range of adapters, and you should confirm you are selecting the correct one for your specific telescope model and mount combination.
Does using the Starlight Instruments 2.0" adapter affect my telescope's back focus?
Yes, any adapter adds length to the optical path. With the FTF2008BCR focuser, the A20-295 measures 2.14" (54.36 mm) racked in and 3.14" (79.76 mm) racked out; you will need to account for this length when calculating the remaining back focus for your imaging train.
