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Old 23-11-2014, 02:00 PM
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SamD (Sam)
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SamD is offline
Join Date: Jan 2014
Location: Brisbane SW
Posts: 71
Originally Posted by HenryNZ View Post
Do you have a figure of your alignment error with polar scope as reported by PHD or PHD Lab?
About 2-4' error, which translates to about 70-140 ms of dec guiding per minute (at 0.5x auto guide speed). I prefer to have a bit of error in polar alignment. I find it easier to always guide declination in the same direction in PhD, and avoid oscillating N/S dec guiding.

As a one-time job, I found it quite fiddly to align the reticle inside the polarscope (with the star patterns on it) with the true pole (tiny allen bolts). I think mine is slightly misaligned, but luckily it seems to give me the amount of error (2-4') I need for reliable dec guiding in PhD !

If an error of say up to 5' is going to give you problems with field rotation on longer exposures, then a polarscope alone may not be the best way to go - you would still need to do drift alignment.
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