double arm barn door drive
I made this drive to take pictures of the comets hyakutake and hale bopp . The drive enables long exposures of the stars and celestial objects without the stars exposing as streaks on the film. The screw is turned one revolution per minute to match the rotation of the earth . In practice, i turned the screw one quarter turn every 15 seconds for exposures lasting up to 3-5 minutes . A beep on a micro cassette recorder (this was the 1990's) cued me when to turn the screw .
Detailed information about this kind of drive can be found here
To set up the drive for imaging, you needed to point the hinge of the device at the north star - I mounted a small spotting scope along the hinge to make this easier . Mounted on the drive is my Nikon F2 with 18mm f 3.5 lens, and my Nikon FM2 with 50mm f 1.2 lens (I no longer have the F2, and sadly, the 50mm f 1.2 lens was stolen many years ago) . I still have the drive and theFM2 . Normally I would just mount one camera when using this, but it did have the capability of driving two at the same time .