SCT Collimation without Tools: BOB'S KNOBS
It's easy . . . just grab a Bob's Knob and turn. You can even do it while looking through the eyepiece on most scopes. And you'll never drop that pesky little Allen wrench or screwdriver on your corrector plate, or in the grass again. Installation is a snap with included instructions, and you can undo the modification at any time.
In particular, this model:
Fits: Celestron 9.25 inch (23.5 cm) f/10 SCT versions with metric M3 screw threads (CPC 925).
Knobs: Black-oxide steel, 12 mm (1/2 inch) diameter.
Threads: Black-oxide steel.
Note 1: The factory dust cover will fit normally with Bob's Knobs installed.
Note 2: The CPC 925 SCT requires knobs with metric threads. The CPC 925 secondary can be identified by 1) a factory-installed plastic cover over the collimation screws; 2) black Phillips factory collimation screws; and 3) brand information on the inside of the housing. Do not use these knobs on the CPC 925.
Note 3: Celestron 9.25 inch SCTs manufactured prior to 2006 have standard 6-32 collimation screws and require knobs with standard threads. These telescopes can be identified by 1) no writing inside the secondary housing (except for the serial number); and 2) most have silver factory collimation screws (photo). Do not use metric knobs on these telescopes.
Note 4: A few non-CPC 9.25 inch scopes manufactured in 2006 have black Phillips factory collimation screws that aren't metric. If your scope's secondary housing looks like this, it requires knobs with standard threads.
Installation instructions are available in English, Spanish, German, Italian and French.