Bob's Knobs are the BEST option for tool-free collimation.
Simple to fit and easy to use.
Collimate your telescope without an Allen key or screwdriver!
Instructions are supplied but can also be found online as well as useful FAQ.
Images are representative and may not show the exact knob size / threads.
IMPORTANT: Please ensure the Bob's knobs threads and factory screw threads match before installation.
Knobs for C9.25 f/10 Secondary (non-Fastar) with Metric Collimation Screw ThreadsPart:
C9.25metBO (black oxide steel); C9.25metSS (stainless steel)Fits:
Celestron 9.25” (23.5 cm) f/10 SCT versions with metric screw threads (CPC 925). Not for C9.25 with “Triffid” Faster or EdgeHD optics.Knobs:
Black oxide steel (black) or stainless steel (silver), 12 mm (1/2”) diameterThreads:
Black oxide or stainless steel
- Black Phillips factory collimation screws usually have metric threads, but some black Phillips screws have standard threads. Our hints will help you determine which screws are on your telescope. Make sure the knob threads match the factory screw threads before installing the knobs.
- Black oxide steel (shown in photo) is for dry environments. Lightly oil the knobs periodically as an anti-corrosion measure. Stainless steel provides better corrosion protection in coastal or high humidity areas, or in places where dew or other condensation is common.
- These knobs sit inside the tall lip around the perimeter of the secondary, so they may be hard to grasp with two fingers. Adjustments can be made using a thumb or finger against the inside edge of the knob.
- If your telescope has the “Triffid” Fastar rotary cover, these knobs will not fit.
- The factory dust cover will fit normally with Bob's Knobs installed.
- If your telescope has a factory-installed plastic cap over the collimation screws, it must be removed and set aside when Bob's Knobs are installed. The cover is cosmetic only and will not affect operation of the scope.