These knobs make it easy to collimate your Celestron C14 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 is a long reach, you can probably still adjust the collimation 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 all 14" Celestron Schmidt-Cassegrain telescopes that use recessed headless set screw-style Allen or slotted collimation screws, including those with the "Trifid" rotary secondary housing that has a cover with three raised legs that rotate to cover and uncover the collimation screws. If your scope has the rotary "Trifid" secondary cover, the cover must remain open after these knobs are installed. The cover is cosmetic only and will not affect the operation of the telescope. The Bob's Knobs collimating screws themselves are made of black anodized aluminum alloy. Their knobs are black plastic, 19 mm (3/4") 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). 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.
Some versions of the C14 have a fourth screw in the center of the secondary housing. This central screw usually holds the secondary mirror assembly to its housing. The collimation screws, which are typically headless set screws, press against the mirror mounting plate rather than threading into it. When installing your Bob's Knobs on these scopes, it's still important to remove only one collimation screw at a time to reduce the risk of rotating the secondary mirror and disturbing its alignment with the primary mirror. Do not adjust the center secondary screw if present.
Some scopes with the Fastar option have a fixed central knob mounted on the secondary housing for the user to hold while unscrewing the outer ring. The three collimation screws on this telescope thread into the secondary mirror mounting plate and hold it in place. As with the non-Fastar scopes with a central secondary screw, do not attempt to adjust this central Fastar knob.
