Telephoto (Zoom) Lens Electric Focuser
I periodically image widefield targets that require low focal lengths like 100 mm. To aid in focusing these lenses I designed a focusing mechanism much like the one Steve Mandel designed.
I purchased two Losmandy-Style Dovetail Plate Adapters (10) to attach to a Losmandy-Style Mini-Dovetail Bar (11) on my C8. These were purchased from Anthony Davoli Machining. The adapters have 1/4" holes, so I drilled two holes into a Robofocus Motor Plate (9)1/4", then attached 1/4 X 20 fasteners and wing-nuts (8). I took a second Robofocus Motor Plate (3), bent it at a 90 degree angle at the appropriate place, and attached it to the first plate via supplied screws and nuts. It is attached so it can slide on the other plate for the proper tensioning. The second plate was hacksawed to allow the sprocket gear (2) attached to the Robofocus Motor (the one for LX200) (7) to protrude through. The motor is mounted via supplied screws and nuts (4). The timing belt (1) was purchased by McMaster Carr . The part number was 684K119. However, I ordered many different sizes. They aren't very expensive, and it's a good idea to order different sizes. The unused ones are returnable and refundable.