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Old 29-10-2018, 08:50 AM
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speach (Simon)
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flats darks etc

I've just started lrgb imaging so this may seem a simplistic question, for each filter is it required to take darks and bias frames, for the flats yes it would be as dust can be on the filters but for the other two types the same pixels would fire off when the filters are changed.
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Old 29-10-2018, 08:53 AM
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multiweb (Marc)
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Just checked that it's not April 1st so I'll have a go at it. If you plug your scope to shoot bias and darks I'm pretty sure color is not an issue.
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Old 29-10-2018, 11:38 AM
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What Marc is getting at is that most folks will shoot darks and bias frames with the scope lenses cap on. So you only need one set of each. As far as flats are concerned, honestly I never use them. If you keep your filters clean, and your camera and scope optics, there is no need. Of course, you did not mention what type of camera you are using, that might help. If your using a cooled camera, then shoot all your bias and darks at the temperature you plan to shoot your lights at. Build a library of darks and bias frames, darks for each of your typical exposure times. Some cameras are so smooth and dependable (like the ASI1600) that you can produce consistent images simply by reusing darks and bias frames from your library (ie, don't shoot them at every session). But do what you please.
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Old 29-10-2018, 01:10 PM
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As far as flats are concerned, honestly I never use them. If you keep your filters clean, and your camera and scope optics, there is no need.
Flats also correct for vignetting and variation in sensitivity between pixels (which causes fixed pattern noise.) I doubt that you'll find many folks producing high quality astro images that don't do flat-field correction.
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Old 29-10-2018, 01:36 PM
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multiweb (Marc)
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+1 Always calibrate your subs. Flat fielding is a part of it.
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Old 29-10-2018, 06:04 PM
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Flats also correct for vignetting and variation in sensitivity between pixels (which causes fixed pattern noise.) I doubt that you'll find many folks producing high quality astro images that don't do flat-field correction.
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+1 Always calibrate your subs. Flat fielding is a part of it.
So true !!

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Old 29-10-2018, 06:25 PM
glend (Glen)
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Flats also correct for vignetting and variation in sensitivity between pixels (which causes fixed pattern noise.) I doubt that you'll find many folks producing high quality astro images that don't do flat-field correction.
Yeah thanks for jumping on that, but I am simply not obsessive about it. I grant you that vignetting is a good reason but my equipment doesn't have any, nor do I have any fixed pattern noise in my images.
I guess I need to learn to keep my mouth shut and let the experts answer any question.
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Old 29-10-2018, 07:44 PM
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multiweb (Marc)
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Yeah thanks for jumping on that, but I am simply not obsessive about it. I grant you that vignetting is a good reason but my equipment doesn't have any, nor do I have any fixed pattern noise in my images.
I guess I need to learn to keep my mouth shut and let the experts answer any question.
Actually posting questions, answers and communicating is how we all learn. There's no experts here.
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Old 29-10-2018, 08:28 PM
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Yeah thanks for jumping on that, but I am simply not obsessive about it. I grant you that vignetting is a good reason but my equipment doesn't have any, nor do I have any fixed pattern noise in my images.
If you have a system without optical non-uniformity or sensor FPN then I look forward to your Nobel prize, Glen.

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Actually posting questions, answers and communicating is how we all learn. There's no experts here.
Amen. We're all wrong on occasion but I try to limit the number of occasions by restricting my comments to things I (think) I understand.
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