GSO Focuser Collimation Ring / Tilt Adapter

The GSO FF672 collimating ring helps improve image sharpness when using your 10 or 12 closed-tube GSO Ritchey-Chretien telescopes (of any vintage) or 10, 12, 14 or 16 GSO Ritchey-Chretien telescopes made up to 2016. An easy way to tell is to look at screws on the rear of your ...The GSO FF672 collimating ring helps improve image sharpness when using your 10 or 12 closed-tube GSO Ritchey-Chretien telescopes (of any vintage) or 10, 12, 14 or 16 GSO Ritchey-Chretien telescopes made up to 2016. An easy way to tell is to look at screws on the rear of your telescope just around the focuser where it attaches to the OTA.

If there are no screws or three pairs of screws, then your telescope can benefit from this accessory. The ring allows you to slightly adjust the tilt of the telescope’s focuser so it’s square with the axis of the telescope’s optics. Such adjustments are sometimes required to counteract the small and unwanted tilt of the focuser induced by machining tolerances in the threads of the telescope’s focuser and rear cell.

This is especially important when imaging with cameras with larger full-frame sensors. The FF672 collimation ring fits between the rear cell of your telescope and the focuser/camera assembly. The ring consists of two spring-loaded components with push-pull collimation screws that let you adjust the tilt angle and then lock the position in place.

The telescope side of the ring has M117x1 female threads that connect to the threaded rear cell of the telescope or to appropriately threaded extension rings. The camera side of the collimation ring has M117x1 threads to attach to your focuser. The ring takes only 15mm of back focus.

When installed, the focuser collimation ring will cover the primary mirror collimation screws on the rear cell of your telescope. To ensure enough clearance for these screws should you need to adjust them, you may need to install at least one of the 117mm extension rings supplied with your telescope.