23272Re: What the heck....a donut near M81?
- Feb 2, 2004Thanks for all the suggestions!
Actually I am very methodic about flats and have wrapped the camera
and drawtube with cloth for some time now. What is perplexing this
time around is that this effect seems to only happen with the
Schuler Ir blocking luminance filter. I note the artifact is present
both in the luminance flats as well as the luminance image frame. I
also took RGB filtered shots of the same object and neither the flat
frames nor the object frames had the artifact present. The filter is
spotless so perhaps I am dealing with a reflection issue?
It almost seems as if the flat field is correcting too strongly or
perhaps not enough. Guess I'll go back to shooting with the SBIG
clear that didn't exhibit any of the odd effects.
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