Fits: 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, 10 mm (3/8”) diameter
Threads: Stainless steel
- 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.
- 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.