Quote:
Originally Posted by garymck
Your customer is never going to be able to do 5 minute exposures in altaz configuration. The limit will be somewhere between 5 seconds and 30 seconds (can't recall how to calculate it exactly) depending upon how high the object is in the sky - longer exposures will always show field rotation even if autoguided. There is no way around this unless you add another piece of equipment (field derotator)...The stars will always be elongated, less if autoguided - perhaps macaroni rather than fettuccini length :-)
Gary
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Thanks Gary. I was kinda afraid this was going to be the outcome. Because I'm on an alt-az I'm totally unfamiliar with field rotation. I think there's a wedge for the CPC 800. I'm no fan of wedges, as it makes the mount unstable, but this might be his only option.
Bill