Quote:
Originally Posted by Dave Smith
Most people on this forum will not have access to a driven mount but may still want to have a go at some astrophotography.
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Those are very nice pictures.
I'm sure you know this, but I'll mention this for anyone here of a DIY pursuasion. (I know Don fits that category.) A cheap home made alternative to an expensive driven mounting is the Haig Mount, also known as the Barn Door Mount, or the Scotch Mount.
http://www.astronomyedinburgh.org/pu...otography.html
I remember the article appearing in Sky and Telescope about 30 years ago and I made one when I was (just) in my teens.
The link explains the principle, but it is no more than two squares of wood, joined by a hinge along one side, with a screw thread passing through one plank, and pushing against the other. The trick is to align the hinge with the Earth's axis, and then turn the screw thread once a minute, thus forcing one of the planks to rotate about the Earth's axis, countering the motion of the stars. The result is that a camera mounted on the moving plank will track the night sky. I think the inventor tried a 200mm lens but it really excelled with wide angles.
I have toyed with the idea of making another one, but the problem is the drive. Mine was digital (I used one finger to push a clothes peg attached to the drive rod). But ideally it should use a stepper motor with associated circuitry and a battery. If anyone knows a good source of the electronic items I would love to know.