Celestron C4-R, C6-R, C6-RGT, Firstscope 102; Orion AstroView 100 EQ / 120ST EQ, SkyView Pro 120; Synta / Sky-Watcher (Pro Computerized) 100ED-EQ5P, 120ED-EQ5P, 120AR-EQ5P, 150AR-EQ5P, (Pro Manual) 102AR-EQ5M, (Pro Refractor OTAs) P80 ED-APO, P100 ED-APO, P120 ED-APO What is an Event Horizon Telescope Focuser?The Event Horizon Focuser (EV) is a low-profile, friction-drive focuser designed for both the amateur and professional market. The highly acclaimed Crayford design (see below) permits tolerances up to 100 times better than conventional rack-and-pinion focusers. Zero image shift and zero backlash makes it fantastic for visual and photographic work and a must for CCD imaging. The modular design makes changes and upgrades extremely easy to accomplish. Add the optional variable-speed Motor and Smart Focus or Digital Readout (DRO) for the ultimate focusing system. The EV is truly a masterpiece of engineering and workmanship that you will be proud to own for years to come.
One of the EV focuser modular bases is designed for Cassegrain telescopes. The most popular type of Cassegrain telescope is the Schmidt-Cassegrain Telescope (SCT). These telescopes achieve focus by moving the primary mirror. This design tends to create image shift which is especially problematic for CCD imaging. The EV Cassegrain focusers achieve focus by moving the eyepiece, camera or other equipment at the back of the telescope instead of the mirror.
Here are a few key features of the Event Horizon focusers: