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Old 17-06-2014, 11:57 AM
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Shiraz (Ray)
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Join Date: Apr 2010
Location: ardrossan south australia
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thanks for persevering H - appreciated

Pretty sure your target ADU is right .

Using the cursor, you really only need to take one background sky sample somewhere well away from the glare of very bright stars and where the sky also has no obvious faint stars. Maybe take a few samples to get a general idea of what the average signal is, but even one single sample should be good enough to get the exposures about right, provided the cursor is not sitting directly on a star.

If you had Antares in the image, you would get some very high readings in part of the image. You need to use the minimum value returned by screen stretch, but that will slightly underestimate the sky signal in the centre of the field. I would recommend just sampling under the cursor as above.

edit: just looked up how Maxim works - suggest that you use the information widow in aperture mode and take the median from a region of sky with as few stars as possible - I think that a single sample taken that way will do the job. It should be quick and easy.

regards Ray

Last edited by Shiraz; 17-06-2014 at 12:29 PM.
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