JMI Telescopes MOTOFOCUS is a motorized electronic focusing mechanism that affixes to your telescope's focuser knob. MOTOFOCUS operates off of a supplied 9-volt battery; with a bit of practice, you'll be able to adjust your focuser in increments much smaller than the width of a business card. In particular, springing for the MOTOFOCUS gives you much more enjoyable high-magnification viewing from your scope, with finer control over the image and much less user-induced vibrations.
This particular version of MOTOFOCUS works with an extensive list of refractors: Celestron's C4-R, C4.5, C6-N, C6-R, C6-RGT, C8-N, C8-NGT, C10-N, C10-NGT, C60, C70, C100, C102, CR-150, Firstscope 80, G8-N, NexStar 80, Super Polaris 80, and Super Polaris 102, Konus' 120mm & 150mm refractors, Meade's 6-10" equatorially-mounted Starfinder, 6-16" Starfinder Dobsonians, #71 and #77 focusers, Orion's Astroview 120, ShortTube 80 & 90, SkyQuest XT4.5/6/8/10, SkyView Deluxe 4.5/6/8 EQ, SkyView Pro 6/8/100/120 EQ, 6LT EQ, VX80, VX102 GP, Skywatcher 120, and 1.25" or 2" rack-and-pinion focusers manufactured by Vixen, Sky Instruments' Antares 120, the Synta Sky-Watcher rack-and-pinion focuser, and all Vixen 2.7" refractor focuser.
If you opt for it exclusively at the time of this purchase, you can also have a numerical expression of your focuser position. The economical DFC Digital Focus Counter is an accurate 3-digit mechanical counter which "piggybacks" upon the MOTOFOCUS, and requires no batteries or hand controllers beyond what you'll already be using.
The much more sophisticated DRO Digital Readout is a 4-digit LED that can attach to MOTOFOCUS and other JMI Telescopes focusers. Beyond a finer expression of focus position, the DRO also offers the capacity to be controlled remotely via a computer as well as to be removed and reattached without needing recalibration.
If choosing the DFC or DRO upgrades, you must do so at the time of this purchase-they cannot be retroactively fitted to the MOTOFOCUS.