Optec's FastFocus Secondary Mirror Focusing System with FocusLynx Controller has proven itself to be a singularly unique solution to the limited back-focus of the Celestron EdgeHD telecopes. With the FastFocus system in place, any Fastar compatible Celestron OTA can function like many professional telescopes where only the secondary mirror moves to adjust the focus. The primary mirror and entire imaging train can be locked in place avoiding flexure and tilt at the image plane.
FastFocus is easily installed taking advantage of the removable secondary mirror of the Celestron Fastar system. The FastFocus system solves a number of problems for users of Celestrons larger SCT's. First, as already mentioned, it solves the problem of mirror flop with the Edge models as their Mirror locks cannot be used if primary mirror focusing is retained. Secondly the Edge telescopes have a back focus distance of 146mm in either standard or reduced configuration. If a focuser is placed on the back of the telescope all you can actually do is vary this back focus distance. While you will be able to change focus with a rear mounted focuser, you will also affect the corrected field. This is not an issue with secondary mirror focusing as this is done before the correcting elements in the Edge models. If using the C models, a focuser can be fitted to the rear of the scope and a corrector after that. However there is limited back focus available and use of a corrector like a reducer is often not possible as it needs to be placed directly on the telescope. The Optec FastFocus system solves all these problems.
To operate the Fastfocus, a focus controller is required. This is either the Optec Focuslynx or a suitable alternative controller such as that found in the Pegasus Astro Ultimate Power Box v2