Fits: Celestron 11” (28 cm) f/10 SCT versions (metal or carbon fiber tube) with standard thread factory collimation screws and "Trifid" rotary cover Fastar secondary housing. Factory collimation screws are silver Phillips. These knobs will also fit the C11 with Starizona Hyperstar if the collimation screws have standard threads.
Knobs: Black plastic, 16 mm (5/8”) diameter
Threads: Black anodized aluminum alloy
- These telescopes can have factory collimation screws with either standard or metric threads. Silver Phillips collimation screws are standard thread. Some black Phillips collimation screws are also standard thread.
- 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.