This dual axis motor drive, with drive corrector capabilities, is designed for Celestron's CG-4 mount. It precisely controls the telescope's tracking speed during long, timed exposures of celestial objects, producing the best possible image sharpness. Precision drive correctors are a must for those with a serious interest in astrophotography or CCD imaging. Four speeds are available-1x (sidereal), 2x for guiding, 4x, and 8x for centering.
These precision, state-of-the-art DC motor drives operate from 4 D-cell batteries (not included). The hand controller module is very compact and fits easily in the palm of your hand. Motors for both axes are included, along with brackets, clutches and hardware.
The Celestron MD-4 is commonly used for Astronomy and more.
Reviewed by 4 customers
Tracking is surprisingly good with very low battery drain (don't use rechargeable batteries though - they don't supply enough voltage). However the circuit boards are exposed to the elements and can be easily damaged or broken off even with careful use. The battery holder is especially cheap in construction with very fragile soldering connections. Despite the accurate tracking, this unit is very overpriced due to poor construction.
Does what it's supposed to, and has a clutch release for DEC adjustments via knob. However, doesn't allow for using RA knob to do any adjustments (requires use of controller).
The drive is the real reason for buying a GEM mount. With this drive, things stay put rather than drifting off even as the earth turns; you do have to do at least a rough alignment on Polaris though. The installation instructions were weak as they were on the scope itself but a little fiddling and I got it. You lose the ability to use the slow-motion control for RA but the declination slow motion control can be used via a manual clutch knob. Normally, I make fine adjustments using the control box; however, it is sometimes very slow to start moving. Large adjustments are made by using the mount's two clutch knobs to get it as close as possible. My unit also has a slide switch which is a little twitchy and sometimes requires jiggling to get it to turn on.
These motors are the best investment I made for my new Omni XLT 150. They make your viewing sessions so pleasing. When sharing the night with others such as friends and family these motors are priceless. Allows me to even use 4m with a 2x barlow (highest magnification I have) and still stays right on taget while everyone takes a peak. Not to mention when viewing at this magnification and trying to use the manual knobs you get some vibration and shakiness. I highly recommened this to anyone buying a cg-4 mount.