Now there is no more tools needed to make collimation adjustments to your telescope! It's easy . . . just grab a Bob's Knob and turn. You can even collimate while looking through the eyepiece on most telescopes. What's more, you'll never drop that pesky little Allen wrench or screwdriver in the grass again. Installation is a snap with included instructions, and you can undo the modification at any time.

The C8 Metric Collimation Knobs (Black Oxide)

Fits: Most Celestron 8” (20 cm) f/10 SCT made in 2005 and later with black Phillips factory collimation screws that have metric threads. Includes Sky-Watcher SCT, non-EdgeHD Fastar, and the NexStar 8SE. These screws have metric threads. It is important that you choose the correct style Bob's Knobs for your telescope. Please note the number and type of screws on your secondary housing before ordering.

These knobs will fit only 2005 and later C8 models that have black Phillips factory collimation screws.

Note: All C8 models made prior to 2005 and all post-2005 models with silver factory collimation screws require C8 standard thread knobs. Check that our screw threads match the factory screw threads before installing.

A: 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. (Photo shows Bob's Knob's installed on a C8 with black Phillips collimation screws. Click our "Images" tab to see a picture of the screws without Bob's Knobs installed.)

B: These knobs will fit the metric Fastar version only if it does not have EdgeHD optics. Scopes with EdgeHD optics require different knobs (as listed below).

C: Black oxide steel (shown in photos) is for dry environments. Lightly oil the knob top and knob serrations periodically as an anti-corrosion measure. Stainless steel provides better corrosion protection in coastal or high humidity areas, or in places where dew or other condensation is common.

D: The factory dust cover will fit normally with Bob's Knobs installed.

E: 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.

• Compatibility: These knobs will fit only 2005 and later C8 models that have black Phillips factory collimation screws. All C8 models make prior to 2005 and all post-2005 models with silver factory collimation screws require C8 standard thread knobs.
• Check that these screw threads match the factory screw threads before installing.

• Bob's Knobs C8 Metric Collimation Knobs - Black Oxide