This JMI Motofocus electric focuser is designed for use with the Celestron C8 Schmidt-Cassegrain, as well as the Celestron CPC 800 and CPC 925. It works with all C8 versions built after 1974 (specify the age of the telescope if it was built prior to 1979). It also works with the NexStar 8 GPS, but not with the non-GPS standard NexStar 8i. A full list of telescopes this focuser will work with is at the bottom of this copy.
The focuser consists of a plastic replacement focusing knob, a plastic focusing collar, DC motor, hand control, and all necessary mounting hardware.
The telescope focusing knob is removed using the supplied Allen wrench and the supplied plastic focusing knob is installed in its place. The focusing collar attaches in minutes to the rear cell of the telescope, around the new focusing knob, using a supplied Allen wrench. The push-on DC motor slips over the focusing collar. A rubber O-ring inside the motor provides a secure grip on the focusing knob that is centered within the focusing collar. The motor is held in place on the focusing collar by a nylon thumbscrew in the motor housing. The motor can be easily removed for traveling or storage. The motor has electromagnetic braking for very precise control. The O-ring gripping the focusing knob acts as a slip clutch to prevent damage if the normal telescope focuser travel is exceeded. The telescope focuser can still be used manually if the electric focus motor is removed from the focusing collar, which can be done in only 10-15 seconds.
A small hand control box plugs into the coiled cord permanently attached to the push-on motor. The control box holds a 9-volt battery (supplied) that will power the focuser for 6 to 8 months of normal use. Pushbuttons control the direction of focuser travel, while a switch-selected 3-speed control adjusts the focusing speed.
Celestron telescopes this focuser will work with include:
early C5 with dual fork arms;
fork mounted C8+, Classic 8, Super C8, Super C8+, C8+, Celestar 8, Powerstar 8, NexStar 8 GPS, Ultima 8, Ultima 2000, CPC800; and
German equatorial mount Polaris C8, Super Polaris C8, Great Polaris C8, C8-S, C8-SGT, CGE-800, G-8, CPC 800, CPC 925..