Collimate your Catadioptric or Newtonian reflector style telescopes without tools!
It's easy...just grab a Bob's Knob collimation thumbscrew and turn. You can even do it while looking through the eyepiece on most scopes. These thumbscrews are also much easier to use with gloves on. And perhaps most importantly, you'll never drop that pesky little Allen wrench or screwdriver into the grass again. Installation is a snap with the included instructions, and you can undo the modification at any time.
Fits: Celestron 11" (28 cm) f/10 SCT versions (metal or carbon fiber tube) with standard (non-metric) 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
1. 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. See our hints for more information.
2. The item listed on this page is the one with the standard (non-metric) thread. The metric thread version of this knob (Bob's Knobs item # C11metfst) is sold separately.
3. The factory dust cover will fit normally with Bob's Knobs installed.
4. 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.