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Old 17-05-2016, 10:11 PM
Rob Hamlin
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Help diagnosing lines in Flats

Hi All

Im running an Sbig STF8300M.

Am finding my HA, SII and LRGB flats have a grid pattern running through them.

OIII flats quite oddly, seem far smoother and dont have the issue. Somewhat baffled about this.

The image ive attached below shows what I see on-screen.

The grid pattern seems quite clear and im not entirely sure how big a problem this actually is.

Any feedback thoroughly appreciated

With thanks

Rob Hamlin
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  #2  
Old 17-05-2016, 10:44 PM
glend (Glen)
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How are you shooting your flats? Looks like a cloth weave pattern.
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Old 18-05-2016, 07:57 AM
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multiweb (Marc)
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Could be a reflection of the micro lensing on the chip when the light source for the flat is too bright and the exposure too short. Try to dim the light and lengthen the exposure see if it looks better.
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Old 18-05-2016, 08:49 AM
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RickS (Rick)
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What ADU levels are you getting in the Ha and Oiii flats?
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Old 18-05-2016, 09:01 AM
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gregbradley
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Did you subtract a bias or flat dark from the flat? Its fixed pattern noise.

Greg.
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