Re: Field Rotation


christian viladrich
 

Hello,

Years ago, when professionals used large Schmidt telescopes with large photographic glass plates, they change the polar elevation of the mount according the photographic field in order to minimize field rotation.

I think I have the calculation somewhere in a book. But not sure this is relevant now, even for 24x36 mm CCD sensor and 30 min integration time😉

Christian Viladrich


Le 28/05/2022 à 16:57, M Hambrick a écrit :

Am I correct in my thinking that field rotation is inevitable even on a perfectly polar aligned mount ? I seem to recall reading that somewhere on this forum.

Regardless, are there techniques besides good polar alignment that will minimize the amount of field rotation that occurs during a long series of guided exposures ? A couple possible things come to mind: 

  • Guide star selection (farther away from the axis of rotation)
  • Multiple star guiding
  • Having a mount with absolute encoders.
Mike

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