Flat field critical warning for wrong reason

That's because you didn't use Darks I believe..

It doesn't have anything to do with the ISO really (as in those of the lights) it has to do with needing a bias, required to normalize the flats that needs to be of the same ISO as the lights. Looking at the files it does seem you successfully created a masterbias and masterflat, those were created in this same session? What is your workflow exactly, maybe that sheds some light on it.

My workflow is very simple now thanks to the DNG support! Thanks again for that!

I leave all settings in the default position and load light, flat and then bias frames - I have yet to do darks but will be trying that today.

Then simply click "Create masters and assign to lights" in tab 2.

Then after the MB is created I see that critical warning. I click OK and processing continues.

Then the MF is created and everything seems to be ok. Just that I'm getting the warning unnecessarily.

That indeed is strange, I'll tag Mabula @mabula-admin so he can have a look at it.

APP always issues a warning if flats are used without either bias or dark or both.

Hi @astrogee, @maaxx & @vincent-mod,

APP always issues a warning if flats are used without either bias or dark or both.

Indeed, for proper flat-field calibration the flats need to be calibrated with either bias, darkflats or both.

It doesn't have anything to do with the ISO really (as in those of the lights) it has to do with needing a bias, required to normalize the flats that needs to be of the same ISO as the lights.

Now, this is not entirely correct. To properly created a masterbias to correct light frames. The flats need to be corrected with a masterbias that has the same iso/gain as the flats.  If the lights have a different ISO/gain value compared to the flats, then you would need 2 masterbiases of the respective ISO/gain values. That is the correct way to calibrate data. Flats can have a different iso/gain value compared to the lights, that is no problem with the camera's these days. (If you have a VERY old camera that does not behave linearly, well then please use the same iso to prevent problems.)

Now since a Masterbias has been created that has the same pixel dimensions as the flats, the warning should not be there. Since APP issues a warning here, it seems that the flats and bias are not matched so I suspect the flat-field calibration is not working as it is supposed to be here.

@astrogee, can you upload a couple of bias and flats and lights (maybe 3-5 of each ?) so I can check what is happening and make sure it works correctly?

https://ariesprodstor.astropixelprocessor.com:7001/

login and password: appuser

Create a folder with your name and let me know once uploaded, then I will have a look as soon as possible.

Kind regards,

Mabula

Hi Mabula, Thanks for responding. I'm having trouble with the security on the link you gave me so I'll have to get back to you a little later. Maybe I should use an FTP client? Had one somewhere but can't find it right now :-s

I had this for my process I just did now. I have:

Lights (Gain=200, Exposure =300s, Temp -20C)

Darks (Gain=200, Exposure = 300s, Temp -20C)

Flats + DarkFlats of same exposure lengths.

No Bias

I got the warning up during Calibration. I cleared it. I processed again after thinking I missed something and then didn't get the error. I was doing multi-session + multi-filter. As far as I could see I checked all boxes yet APP complained.

Posted by: @mabula-admin

Hi @astrogee, @maaxx & @vincent-mod,

APP always issues a warning if flats are used without either bias or dark or both.

Indeed, for proper flat-field calibration the flats need to be calibrated with either bias, darkflats or both.

It doesn't have anything to do with the ISO really (as in those of the lights) it has to do with needing a bias, required to normalize the flats that needs to be of the same ISO as the lights.

Now, this is not entirely correct. To properly created a masterbias to correct light frames. The flats need to be corrected with a masterbias that has the same iso/gain as the flats.  If the lights have a different ISO/gain value compared to the flats, then you would need 2 masterbiases of the respective ISO/gain values. That is the correct way to calibrate data. Flats can have a different iso/gain value compared to the lights, that is no problem with the camera's these days. (If you have a VERY old camera that does not behave linearly, well then please use the same iso to prevent problems.)

Now since a Masterbias has been created that has the same pixel dimensions as the flats, the warning should not be there. Since APP issues a warning here, it seems that the flats and bias are not matched so I suspect the flat-field calibration is not working as it is supposed to be here.

@astrogee, can you upload a couple of bias and flats and lights (maybe 3-5 of each ?) so I can check what is happening and make sure it works correctly?

https://ariesprodstor.astropixelprocessor.com:7001/

login and password: appuser

Create a folder with your name and let me know once uploaded, then I will have a look as soon as possible.

Kind regards,

Mabula

Hi Mabula,

I'm having trouble uploading. I can't get proper access. Don't I need the home directory for appuser? I get this message:

I put the files in a dropbox here:

Dropbox File (Private or Invalid)

Thanks

Thank you, sorry for the delay, I've been away for a bit as I'm moving (yet again). The server doesn't have a certificate indeed, this seems to be fine for most browsers that only warn about it, but some might have issues. Mabula might look into getting a certificate, but just for sharing data it seems a bit unnecessary maybe.

I'll download the files and have a go myself.

So I tested the files and I first created the master frames which worked fine without warning. Integration completed as well without warning..