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Old 15-10-2015, 01:13 PM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,822
Originally Posted by Rod771 View Post
Geez, I like the sound of this. Taking flats through the Hyperstar lens with a DSLR and LP filter just sucks.

Ray, was the star field sub used for the synthetic flat exposed for the same time as your lights? And am I right in saying, that you only used one DBE extraction image as master flat and this was effective on a large number of light subs?
yes, it was one of the light subs. The DBE background was then applied just like a normal master flat would be - (you must set downsample under model-image to 1 though). It gets rid of vignetting and even helps with the worst effects of large donuts (if you use enough sampling points). It does not do fixed pattern noise reduction, but dither can take care of most of that - it's not as good as a real flat, but still useful if you have problems getting flat data. You don't get a lot of signal in the synthetic flat, but, being a fitted surface, it is essentially noise free. if you do try it, be interesting to hear if it works well enough - I guess there will be issues with a DSLR due to the Bayer filter, but you should be able to find a way round them.

Last edited by Shiraz; 15-10-2015 at 08:31 PM.
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