Dark Frame and Flip

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jsawaski
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Joined: Tue Mar 14, 2017 2:06 am

Dark Frame and Flip

Post by jsawaski » Sun Mar 03, 2019 4:35 pm

When creating and using dark frames the manual is specific about certain parameters being help constant; gain, exposure, temperature, etc. However, "Flip" is not mentioned.

I experimented by creating a dark frame of a brick wall in the daylight. If I apply the dark to a light with the same "Flip" setting I see a black screen; as expected. However, if I set the "Flip" control to anything other than what the dark was created I see a rather ugly image. This make me believe that the dark frame must be used with the same "Flip" setting as the light frames.

This has implication for both EAA as well as post processing astrophotography. I also believe flats would have the same issue.

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admin
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Re: Dark Frame and Flip

Post by admin » Sun Mar 03, 2019 7:05 pm

Hi,

Yes you are correct that you must use flats and darks with the same Flip orientation as the captured frames. I think this is only a problem on ZWO cameras because most other brands of cameras don't offer the option to flip if you are capturing raw frames. I will try to make sure this makes into the documentation for the next update

Cheers, Robin

jsawaski
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Joined: Tue Mar 14, 2017 2:06 am

Re: Dark Frame and Flip

Post by jsawaski » Sun Mar 03, 2019 11:31 pm

Yes, I use ZWO cameras. This expalins why sometimes I such poor results during EAA secissions and some astrophotography images. Knowing this will make a big difference for me.

Is it possible, during live viewing, to make SharpCap check compatibility of all the appropriate parameters of the dark and flat with the current camera settings? And if an error exists issue a warning? The user could ignore the warning, but at least the user was warned. I guess the real question is, are these parameter stored in the FITS file of the master dark and flat?

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Re: Dark Frame and Flip

Post by admin » Mon Mar 04, 2019 7:03 pm

Hi,

I pretty sure that the flip settings will not get saved in the meta data of a master flat or master dark image file, which would mean that SharpCap would not know which flip orientation should be checked and using those frames. Of course I could make it save that data in future, but that wouldn't help for any existing flat or dark file libraries.

I wonder if it might be better to take away the current flip controls and add a separate set that only flip the image on screen and do not adjust the saved image orientation. Then every saved file would have normal orientation and the flip controls would just change how the image looks on screen which is all they are really good for anyway.

Cheers, Robin

jsawaski
Posts: 19
Joined: Tue Mar 14, 2017 2:06 am

Re: Dark Frame and Flip

Post by jsawaski » Mon Mar 04, 2019 8:07 pm

Yes, that sound good.

BlackWikkett
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Re: Dark Frame and Flip

Post by BlackWikkett » Mon Mar 04, 2019 8:37 pm

We've had a request for this from some time back.

viewtopic.php?f=5&t=1279

jsawaski
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Joined: Tue Mar 14, 2017 2:06 am

Re: Dark Frame and Flip

Post by jsawaski » Tue Mar 05, 2019 4:01 am

Apparently I did a poor job of searching to see if this issues was already reported. Sorry for the duplication.

But I guess all that maters is that we make people aware of this and improve Sharpcap.

cmooney
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Re: Dark Frame and Flip

Post by cmooney » Tue Mar 05, 2019 7:25 pm

+1 for having the dark frame follow camera orientation one way or the other. Preferably maintaining orientation to the saved file.
Maybe "mirror, flip, and mirro+flip" could be added as a preview effects FX filter?

I like to run remote EAA Star Parties and I like to have everything north-up on the GEM, so I double flip the camera after a maridian flip.

I only realized the dark fame flip issue recently (just started using the GEM) and I'm planing on stating a new dark frame library and manually labeling "east side" & "west side" dark's. Luckily I'm only using a newt, so I don't have to worry about the different refactor mirror

SharpCap as awesome!
-Corey

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