Flats questions

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HAL
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Flats questions

Post by HAL »

Hi everyone,

So far I haven't been bothering taking flats and have been doing a synthetic flat in photoshop. Today I decided to take proper flats. Two questions:

1. I used the option to capture flat with Sharpcap but what I have ended up with is lots of individual frames saved as .fits files rather than a .ser video that I can use in Autostakkert. I think I should have just taken a video as normal rather than using the option to create a flat. Can I do anything with these .fits files to apply the flat to my images?

2. When capturing flats is it fine to just take one flat per imaging session as long as nothing changes in the optical train and the histogram is roughly similar for all of the images?

Thanks!


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MAURITS
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Re: Flats questions

Post by MAURITS »

I use one flat for all my images, as long you don't rotate the camera.


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marktownley
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Re: Flats questions

Post by marktownley »

I don't use flats sorry.


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Re: Flats questions

Post by allhoest »

1. Yes, take a video record, and create a flat from it.
I defocus little (as less as possible).
I shake the scope during the flat recording.

2. Yes, as you suggest. Furthermore, don't change settings like gain, gamma, etc.
If you use a Ha etalon, wait for the T° to stablize.

CS
Alex


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Re: Flats questions

Post by Hughsie »

I have a 60mm scope and place a crumpled translucent sandwich bag over the front secured by an elastic band. I’ve never had to defocus. I then adjust the exposure keeping the gain the same until the peak of the histogram is around 50%. I then capture a ser file of 25-50 frames then create the master flat in AS3.

During my session I will introduce Barlow/powermates into the image train and will then have to adjust the rotation position of the camera so I have the Sun properly orientated. Whether I adjust the camera rotation or add Barlows I will always take new flats.


Lunt 60mm DS TH⍺ B1200CPT.
ZWO ASI 174mm & tilt adapter.
SkyWatcher EQ6R-Pro.
SharpCap Pro.
Various Powermates and Barlows.
One cat with a love of tripod legs.
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