Darks for Multi-Channel Processing

Hi Dave @jonesdee,

Welcome to the APP forum 😉 and thank your for your question:

In addition to L, R, G & B Light Frames, I have taken Flats and Dark Flats for each channel. As my Lights have differing exposures (L = 60 seconds and RGB = 120 seconds each), I also shot Darks for these durations . When loading the Darks into APP using Multi-Channel processing, I assigned them to the appropriate channel (60s Darks to L and 120s Darks to R, G and B).

Calibration fails, however with critical warnings of missing Master Darks and on inspection I see that although all the expected Master Flats and Master Dark Flats have been created correctly, only one Master Dark has been created and this is assigned to the Luminance Channel, hence there is no Master Dark for R, G or B and flat field calibration cannot complete.

I assume that I am doing something wrong with the Dark frames - can I make a valid Master Dark for all Channels by combining Dark frames of different exposures (i.e 60s and 120s) and assigning these to all channels?

If you assign the darks (with different or same exposure time) to different channels and or sessions, you should end up with different masterdarks for the different channels and/or sessions.

So is this failing in your situation? Can you show a screenshot perhaps of all files loaded when you try to create the MasterDarks?

If I process the channels individually, I get a Master Dark specific to each, however I suspect that this may be an unnecessary workload!

Indeed, that shouldn't be needed.

Kind regards,

Mabula

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Hi Mabula, thanks for having me and thank you for your reply  😀 

I think that I may have found the issue that was causing my problem.  When I load my files, I have always left the 'apply "FILTER" header tag' checked.  When I loaded my 2 sets of Darks today, I assigned the 60 second files to Red, Green, Blue and Hydrogen Alpha; and the 20 second files to Luminance, but the file assignments shown for 60 secs were 'Red, Green, Blue, Hydrogen-alpha Luminance' and the 20 secs were assigned to 'Luminance Ha' . When Calibration was run, only one MD was created from the 20 sec files and called 'Master Dark MD-1 Luminance Ha'.

I reloaded the files with the 'apply "FILTER" header tag' unchecked and the file assignments were shown correctly and Calibration generated the two master dark files as expected.  I have been unable to paste my screenshots into this reply, but have attached 4 files showing the assignments with and without Filter Header tag and the related calibration results.

My Flats and Dark Flats had different exposures for each of the 5 channels, but unlike the Darks, these calibrated perfectly with the Filter Header Tag set by default.

Anyway, I know what to do to overcome the issue and hope that the above is not too confusing! Please let me know if you would like more information on this,

Best regards

Dave

Posted by: Jonesdee

Hi Mabula, thanks for having me and thank you for your reply  😀 

I think that I may have found the issue that was causing my problem.  When I load my files, I have always left the 'apply "FILTER" header tag' checked.  When I loaded my 2 sets of Darks today, I assigned the 60 second files to Red, Green, Blue and Hydrogen Alpha; and the 20 second files to Luminance, but the file assignments shown for 60 secs were 'Red, Green, Blue, Hydrogen-alpha Luminance' and the 20 secs were assigned to 'Luminance Ha' . When Calibration was run, only one MD was created from the 20 sec files and called 'Master Dark MD-1 Luminance Ha'.

I reloaded the files with the 'apply "FILTER" header tag' unchecked and the file assignments were shown correctly and Calibration generated the two master dark files as expected.  I have been unable to paste my screenshots into this reply, but have attached 4 files showing the assignments with and without Filter Header tag and the related calibration results.

My Flats and Dark Flats had different exposures for each of the 5 channels, but unlike the Darks, these calibrated perfectly with the Filter Header Tag set by default.

Anyway, I know what to do to overcome the issue and hope that the above is not too confusing! Please let me know if you would like more information on this,

Best regards

Dave

-- attachment is not available --

 

@jonesdee, Thank you very much Dave for your extensive feedback 😉

Yes, the "apply FILTER header tag" should automatically be disabled when you select a channel yourself. In APP 1.062 that I released today, you will find that that is the case now ;-). So it should now prevent this issue automatically.

Thanks for sharing,

Mabula

No problem Mabula, thanks for the update!  I shall be downloading 1.062 shortly  🙂.

Best regards

Dave

Hi Dave @Jonesdee,

Excellent 😉

Mabula

Thanks Mabula, I have re-processed that data plus a couple more sets using 1.062 and it performs perfectly every time 🙂 

You are making these complicated tasks too easy for us!

Dave

Hi Dave @jonesdee,

😉 that is awesome to hear, thanks for the feedback 😉

Mabula

Is it also possible that the "apply FILTER header tag" is also automatically disabled, when I click "all channels"? It would also help, if the pre-selected checkbox depends on the kind of frame. For Lights and Flats a pre-selection of "apply FILTER header tag" is sensible - in case of Bias and Darks the "all channels" is appropriate.

By the way, why isn't the FILTER header tag from the single flats frames saved in the Master Flat? So I have to manually set the filter.

Cheers, Stephan