Focusing has always frustrated me, especially now that I’m taking a lot of pictures. Humans are not well designed to focus small telescopes with their fingers. Turn the focus knob, and the image bounces around. Wait for it to settle down, and turn it again…
So I built a motorized focuser, based largely on Brian Sumpter’s design. It works great. I bought the servo, switch, and rheostat, but scrounged around for the rest of the parts (iPod case, erector set pulleys, etc.). The breakthrough for me was using a grommet (I had a box of assorted grommets from Harbor Freight) to fit in the drilled out pulley center-hole and over the .5″ focus spindle. I was also happy to figure out a way to attach the servo mounting rail to the scope without tapping any new holes.
Scott's Sky Shots 
For this scope at least, it’s a significant improvement. Take Jupiter: in order to focus the camera, I need to look at the camera LCD screen (or an attached tablet) and zoom in 5x or 10x, and that on top of a 2x barlow. Jupiter jumps around with the slightest touch on the focus knob, and I have to pause frequently during focusing to wait for it to settle. With the controller, it hardly jumps around at all. You don’t have the tactile feedback, which is a disadvantage, but it’s easily outweighed by the steadiness of the image during focus.
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