Knobs: Black plastic, 13 mm (1/2”) diameter Threads: Black anodized aluminum alloy
Notes:
These knobs will fit C8 models made prior to 2005 (except pre-1980 orange tube), and most post-2005 models with silver factory collimation screws.
Most models with black Phillips factory collimation screws require C8 metric knobs (Item C below) A few post-2005 scopes have black Phillips collimation screws with standard threads. Here are some hints
to help determine which screws your telescope has. Make sure the knob
threads match the factory screw threads before installing the knobs.
More information is in our Celestron technical paper.
We
provide spacers to raise the knobs slightly for easier use, but the
spacers can be omitted if the knobs contact the inside of the
full-aperture dust cover. Spacers are required for knobs installed on
the Fastar secondary with silver collimation screws for proper clearance.
Some
telescope versions have a small plastic cover over the factory
collimation screws. This cover 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.
