>
> Two unrelated questions...
>
> 1) Does a field derotator really work well for astrophotography? =20

Apparently, with larger LX200s it works acceptably when photographing
through the telescope. Bear in mind that you can't aim straight up --
it sticks out too far behind the telescope. Also, piggybacking, which
is one of the best kinds of deep-sky photography, remains completely
impossible with the de-rotator. For piggybacking, you have to
polar-align.

> 2) How important is precise drift polar alignment on an LX-200 that
has =
> been aligned electronically using alignment stars? How acurate is the
=
> LX-200 electronic alignment?

The LX-200 does not compensate for polar alignment error in any way.
You have to get it right yourself. However, that is easy to do by
checking drift. There is software (TPoint, from Software Bisque) that
will compute your polar alignment error and tell you what it is.
However, I find it easy to align within half a degree or better by
conventional means, taking just a few minutes of drift-checking, and
that's good enough for astrophotography.

Polar alignment is nothing to be feared!

Clear skies,

Michael Covington
Author, Astrophotography for the Amateur
(Now working on a book on computerized telescopes)
http://www.CovingtonInnovations.com/astro <><
[Astronomy correspondents: Please do not send pictures or
file attachments unless requested. They will not reach me. ]

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