Does anyone have any experience with field rotators?
One way one might do it is to use the eyepiece holder itself as a bearing, and put a worm gear around your T-adapter, and then rotate the camera in the eyepiece holder.
Better would be a T-adapter with an integrated ball bearing and worm gear.
I'd like to build a computer controlled altazimuth mount for my scope. The computer part doesn't faze me. Getting an altaz mount that works well seems straightforward. Rotating a camera at the right rate, accurately centered on the optic axis, smoothly enough for a good long-term exposure, that scares me.
Of course, for eyeball use, one could hook a motor drive up to one of those big wood clamps that cabinetmakers use, and clamp the observers head inside, thereby ensuring that one's point of view rotates along with the scenery.
If one were taking a spectrum of a star, and the star were centered on a slit right on the optic axis, then the star field would rotate around but the star itself would stay there. So one could hang a large spectrograph, or a photometer off the scope without worrying about rotation.
Mike Crawford Mike_Crawford@QuickMail.Apple.Com