Star Tracking Camera Platform

I made this tracker platform a few years ago and I have taken lots of star photos with it. Look at the white tube this is for lining up the mount with the pole star, by setting the camera on B to start the exposure and by rotating the screw at one rev per minute, this counter acts the earths rotation. Exposures of 4 to 5 minutes will show stars fainter than binoculars can show.