Mechanical fine focusser

[scopemankit (Chris)]

Taking images with ccd's and webcams requires good focus. The telescope I have is an f16 Cass and any effort to refocus leads to much wobbling and a settle down period after touching the focuser. I have built a fine focuser which gives the eyepiece/ camera 2.0 mm travel.

The two arms fit over the end of the focus knob. The inner arm, slides over the focuser knob and freewheels. It is anchored to the back of the telescope. The outer arm clamps over the focuser's knob. They form a hinge and the angle of the hinge is set with a 6mm threaded rod driven by an old Panasonic video focusung motor. The motor is driven by 5V power on the hand-paddle, controlled by by a spring loaded two directional switch.

The max movement of the Crayford's cylinder is 2mm.

To use, focus as best you can manually, tighten the clamp and focus up and down until best focus is reached. As there is no wobbling, it is also easier to see slight improvements of the image.

[ZeroID (Brent)]

A cunning plan, so cunning you could pin a tail on it and call it a focusser.

Nice work, you've given me a another new project to play with. I have several miniscule motors with tiny helix driven gears that would lend them selves to adaptation nicely.

Thanks, even though my wife won't be quite as pleased