What's Going On with these Flat Frames [Deep Sky] Acquisition techniques · Jerry Gerber · ... · 9 · 231 · 5

jsg 9.55
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These images below are flat frames taken with the Wanderer Astro Flip-Flat at a remote site, using a ZWO ASI2600MC color camera.  They seem to work fine when I calibrate my lights with them, but they do not look like the flat frames I generate at home in the morning after imaging (sky flats at home).    Anyone know why they look they way they do and if I need to be concerned, what do I do?

Flat frame with UV/IR cut filter:

UV-IR Flat.jpg

With L-Ultimate narrowband filter:



L-Ultimate Flat.jpg

With Askar Ha-Oiii filter:

Ha-Oiii Flat.jpg

With Askar Sii-Oiii filter:

Sii-Oiii Flat.jpg

Thanks for any feedback!
Edited ...
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andreatax 9.89
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I hope you take them at night, not during daylight. Otherwise is typical with some flat panels. Whether they are still do their job properly is hard to say as you'd be shooting with a far lower background brightness at your dark site I expect and you can get away with less then pristine correction that would otherwise be in the case in significant LP settings.
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jsg 9.55
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andrea tasselli:
I hope you take them at night, not during daylight. Otherwise is typical with some flat panels. Whether they are still do their job properly is hard to say as you'd be shooting with a far lower background brightness at your dark site I expect and you can get away with less then pristine correction that would otherwise be in the case in significant LP settings.

Yeah, I take them at night as soon as I am finished capturing the last sub for the evening.
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afd33 9.38
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If they properly calibrate your lights, don’t worry about it. That’s the rule I’ve always lived by for flats.
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Gondola 8.11
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….if you are having flat panel issues you can always do sky flats and do away with an extra bit of hardware. It's the easiest way to make flats anyway, no panels, no t-shirts, just a clear blue sky. For that matter, a brightly illuminated wall indoors works well too.
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Rostokko 1.51
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Those seem fairly normal flats for dual-band filters…
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Wjdrijfhout 6.78
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Look pretty normal. So how do your flats look like that you take at home?
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jsg 9.55
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....if you are having flat panel issues you can always do sky flats and do away with an extra bit of hardware. It's the easiest way to make flats anyway, no panels, no t-shirts, just a clear blue sky. For that matter, a brightly illuminated wall indoors works well too.

Not really possible when the scope is 900 miles away.
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jsg 9.55
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Willem Jan Drijfhout:
Look pretty normal. So how do your flats look like that you take at home?

The flats I take at home (same camera and scope) don't have the multi color areas that the remote flats have.   Is this because of the difference between sky flats and LED flats?

Here's a flat from my backyard, using same camera and filter:


Flat_1.2s_Bin1_2600MC_gain100_20240228-115938_-9.6C_0007.jpg
As you can see, the coloration is much more subdued.  Perhaps the sky flats are dimmer as I use 3 t-shirts over the lens.   There's also the normal vignetting that I don't see  as much in the remote LED flats.
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Wjdrijfhout 6.78
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Don’t see anything particularly strange. Any differences can be well attributed to the different light-sources. And the resulting differences in stretching will also make for some differences in how these images look like.
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