How can I make an eyepiece parfocal with my video surveillance camera or webcam ?
A parfocal ring can be improvised as shown elsewhere on this website, or better still, use a Steven Mogg low cost parfocal ring: The camera is pushed fully into the focusser and the starfield focussed until the stars are sharp points of light. Then the camera is removed and the eyepiece with a loosely fitting parfocal ring is pushed into the focusser until the image is sharp. Then the screw on the parfocal ring is tightened so that the eyepiece cannot slide further into the focusser. The eyepiece is now parfocal with the camera. Thsi will greatly facilitate focussing in the future. Visit Steven’s website for more information (S.J.
