[APML] Ideal STV Guiding Errors?

["Thomas W. Earle" <twade@bmi.net>]

I use the eFinder as a guide scope. I typically keep the corrections
to every 4 seconds.  This supposedly prevents the STV from chasing
the seeing.  I use the drift method for polar alignment; however, it
is difficult in determine how accurately polar aligned I am.  How
accurate of a polar alignment do I need when using a Pentax 67 with
lenses ranging from 45 mm to 300 mm.  I plan to expose E200 from
60-90 minutes at f/5.6.  As a reference, in October, I was getting
average corrections (i.e. AEX and AEY) of 1-2" with instantaneous
reading ranging from 0.0 to 3.0".  Keep in mind, the average values
were being average over a 64 second period.  The seeing that night
was pretty poor given the instantaneous readings.  I saw no field
rotation with my 20 minute exposures.  Are these values common?  Do
these values point to poor polar alignment?  What values are
acceptable to prevent field rotation?

Any suggestions would be greatly appreciated.

Thanks in advance,

Wade  


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