Bill, This design would work well in a frictionless evnironment. I fear that with any friction at all the mechanism would move in small increments that would destroy the image. It doesn't take much. Brent --- bill biesele <xmix@biesele.net> wrote:
If a field derotator is a 1 rpd drive couldn't one be built with a pivot and counterweights? Axis of pivot would be parallel to optical axis, counterweights would hang down to drive rotation at 1 rpd by gravity.
Wouldn't want to use it in a wind, but would it work?
Bill B
Chuck Hards wrote:
Basically, it's a drawtube that rotates, driven by
a
stepper motor via belts or gears. Whatever's locked in the drawtube is rotated with it. They don't need active control, since they are basically just a clockwork mechanism, 1 rpd., but it wouldn't surprise me if they existed with programmable rates or scripting capability. There are commercially-made units; I think even Meade offers one for their 16" SCT when it's mounted in alt-az. mode. But I don't have the details for any off-the-shelf units.
C.
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