The Event Horizon EV-3 is a 2" black-anodized aluminum focuser with knurled knobs. The focuser lifts up to 4 pounds. Manual control is over 1½ times finer than most rack-and-pinion focusers.The Cassegrain version (EV-3c) is designed for use on 6" to 16" Cassegrain telescopes (e.g. SCT and Mak-Cas) with standard output threads. It includes an SCT threaded output adapter to allow use of standard SCT equipment on the output side of the focuser. The focuser gives 1/2" of travel and is designed for fine focus after rough adjustment with the normal telescope focusing knob.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: