The Orion AccuFocus for Dual-Speed Crayford Focusers is a great way to focus your telescope. Instead of focusing by hand, which can cause vibration, you use the pushbutton hand controller for smooth, precise focusing without vibration.
I have a 120ED with great optics, and I'm often using it for quick planetary looks. However, I had some difficulty achieving fine focus between my clumsy fingers and the inherent instability of my Alt-Az mount. I was considering high-end two speed focusers. While they are modern day telescope bling, I decided they were not going to solve the problem without motorization, and by the time I paid for all that the price was looking really steep. I began to develop a theory that maybe the Crayford that came with the scope was quite smooth enough, and I just needed more precision. Enter the Orion AccuFocus. This little guy bolted right on to my 120ED without an issue. The unit has knob that controls the speed of the buttons. The real test of course is high power focusing. When the speed is set low I have plenty of room to find the best focus possible. Now I'm able to spend my quick planetary viewing sessions actually viewing the planets rather than messing with the focus. An easy 5-stars to the AccuFocus for saving my hundreds on a bling focuser!