Evolution of the Camera Clamp

I do much of my work in afocal mode using an ordinary digital camera and these clamps.

Camera Clamp Mark 1 was made of bits of Handy Angle, a whole bunch of 1/4-20 screws, and a soft-alloy clamp thingy that held a timing motor on a Japanese telescope mount. The camera goes on the bolt at bottom. You could almost get the camera centred in the eyepiece by jinking the Handy Angle members and tightening the wing nuts. I've shown it mounted to Southam Observatory's 17.5" Dobson. The Tele-Vue 32mm Erfle eyepiece yields just 62x but only part of the quarter Moon will fit the frame.  Exposures are short enough to avoid trailing.

Here is Mark 2 with its single improvement -- the jack that permits vertical motion of the camera. It was made from an old gaffer's clamp. First, I threaded the rod on the lathe. A disk of aluminum rod was threaded to serve as a camera platform and has a recess for a cork disk. The threaded rod engages the camera socket and is tightened by the knob. One advantage of Mark 2 was that it didn't look like a medieval torture device. When I brought Mark 1 to a star party and walked around looking for scopes to try it on, people overreacted.

Mark 3 is as easy to adjust, yet more professional looking. The 3/16" plate was bored on the lathe to fit 2" eyepieces. (Should have been thicker but it works.) The extra holes were supposed to hold the plate to the lathe faceplate, but they came in handy to hold the rod. The Crappy Tire wrench allows you to move the rod from hole to hole as required. Square 3/4" aluminum stock was drilled to fit 1/2" steel rod. The hole was slitted with a hacksaw. A brass knob, tapped 10-32, is threaded onto a machine screw whose head is visible just above the right end of the yellow tape. When tightened, the knob clamps the stock securely on the rod.

The two thumbscrews hold the eyepiece in the hole. I use a Tele-Vue 55mm Plossl that gives 160x on the Southam Observatory Cassegrain. The camera goes on the tripod screw, and the whole assembly is put on the telescope. With the knob half-tight, the photographer adjusts the camera up-down in-out to try to center it behind the eyepiece. It is also possible to position the camera left-right and to square it up by loosening the tripod screw.