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 C11 f/10 with “Trifid” Fastar Secondary Housing and Metric Collimation Screw ThreadsPart:
Celestron 11” (28 cm) f/10 SCT versions (metal or carbon fiber tube) with metric thread factory collimation screws and "Trifid" rotary cover Fastar secondary housing
. Factory collimation screws are black Phillips. These knobs will fit the C11 with EdgeHD optics
. They will also fit the C11 with Starizona Hyperstar
if the collimation screws have metric threads.Knobs:
Black plastic, 16 mm (5/8”) diameterThreads:
- These telescopes can have factory collimation screws with either standard or metric threads. Most models with black Phillips collimation screws have metric threads. There are a few black Phillips screws with standard threads. See our hints for more information. If you discover your knobs have the wrong threads, you may return your knobs for exchange at no additional cost. Alternatively, you can order knobs with both standard and metric thread screws and return the unused set for a full refund.
- Collimation screws on these telescopes are small with very fine threads. Knobs must be tightened gently (just enough to hold the secondary in place) to prevent damage to either the knob or secondary assembly.
- The factory dust cover will fit normally with Bob’s Knobs installed.
- The rotary secondary cover must remain open when the knobs are installed. The cover is cosmetic only and will not affect operation of the telescope.