| These knobs make it easy to collimate your Celestron CPC1100 for optimum image quality. You don’t need any tools, so you never have to worry about losing a tiny Allen wrench or screwdriver in the grass in the dark. While it may be a long reach for some people, you can usually adjust the collimation by yourself while looking through the eyepiece, so there’s instant feedback about how your optics are performing. Installation of the knobs is a snap with the included instructions, and you can undo the modification at any time. This knob set works with the 11” Celestron CPC1100 Schmidt-Cassegrain telescope only (which uses metric collimation screws). Celestron 11” SCTs manufactured prior to 2006 had standard 6-32 collimation screws. Do not use these metric knobs on those telescopes. The photo above shows the secondary mirror housing with the plastic trim piece that covers the collimation screws installed on the secondary housing. This cover simply snaps into place in the secondary housing and must be removed before you can change the collimation screws. The feature photo below shows a close-up of the secondary housing after the plastic trim piece has been removed. The cover cannot be replaced with the new collimation knobs installed and is no longer used. It is used for cosmetic purposes only and leaving it off the scope will not affect the scope performance. The M3 metric collimating screws themselves are made of stainless steel. Their knobs are black oxide steel, 12 mm (1/2”) in diameter. The factory dust cover will fit on the scope normally with Bob's Knobs installed. The three collimation screws hold the secondary mirror and its mounting plate to the secondary housing. The mirror mounting plate pivots on a tang or spring at its center, and the collimation screws, which are threaded into the plate, adjust the mirror tilt (or collimation). Be certain that the new knob threads match the factory screw threads before installing the knobs. Do not remove more than one of the original collimation screws at a time when installing Bob's Knobs, as the secondary mirror might fall off (if all three screws are removed at the same time), or the secondary can pivot inside the tube, scratching the corrector plate (if two screws are removed simultaneously). By removing only one factory collimation screw at a time, replacing it with a knob, and repeating this process for the other two collimation screws, there's no danger of dropping the secondary mirror. The instructions also recommend pointing the optical tube assembly slightly downward during the installation of the knobs for an added safety measure. |
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