Back to forums

Dark Flats, NB filter and Pixinsight

Pleiades Astrophoto PixInsight Processing Dark Frames Calibration Deep Sky
3 replies•254 views
vsola avatar
vsola avatar
I've recently started using a Pegasus Flatmaster to take my flats. In NINA I'm using dynamic brightness mode and taking Narrow Band Flats of 2 seconds. On a night where I use Ha and SII for example, I take 25 Flats on each filter, NINA then has me cover the scope and proceeds to take 25 Dark Flats for each filter, all at 2 seconds.

When I move to processing in Pixinsight, WBPP groups all of the Ha/SII Dark Flats together because they have the same exposure time, it doesn't consider the filter in the FITS header, like the Flats tab does.

My question is, Does it matter what filter your Dark Flats are taken with?

It seems like it shouldn't matter if the Flats are all the same duration.  It also seems that I could reduce the number of Dark Flats NINA takes per filter and spread my desired total of Darks across the number of filters I am using that night…i.e. if I want 25 total Darks and I am using 2 filters I could tell NINA to take 13 Dark Flats per filter and end up with 26 to make the master in WBPP.

Thanks for taking a look.

Vince
Engaging
Jonny Bravo avatar
Jonny Bravo avatar
No, it doesn't matter. They are darks. There is no light passing through to be filtered. That's why PI doesn't consider the filter, but only the exposure length.

So I don't get a bucketload of extra darks, I set NINA up to do like 50 flats and 12 dark flats per filter, so at the end of it, I have 48 dark flats to turn into my master dark flat that's used to calibrate the flats.

I'm actually impressed you're able to get 2 second flats on narrowband filters with the FlatMaster. I've got the older version of the 150 and my Ha/S2 flats can take upwards of 90 seconds.
Helpful Engaging Supportive
vsola avatar
vsola avatar
Awesome, thank you @Jonny Bravo.  The dynamic brightness options in NINA's FlatWizard  and the new Flat Master has really made things a lot easier for grabbing my calibration data.  No more fiddling with sheets of paper and a tablet.

Thank you for confirming my thoughts on the Flat Darks.

Vince
Respectful Supportive
Jonny Bravo avatar
Jonny Bravo avatar
Awesome, thank you @Jonny Bravo.  The dynamic brightness options in NINA's FlatWizard  and the new Flat Master has really made things a lot easier for grabbing my calibration data.  No more fiddling with sheets of paper and a tablet.

Thank you for confirming my thoughts on the Flat Darks.

Vince

Yes, the FlatMaster certainly helps in that regard. I'm guessing the newer, LED-based versions of the FlatMaster must get far brighter than the older EL panel version like I have. Even with the panel boosted at full brightness, my Ha / S2 flats are still on the order of many tens of seconds. Looking at the last narrowband flats I took using my 294MM in the unlocked mode, gain 108, offset 20 through Chroma 3nm Ha/S2 filters and my 0.8x reduced GT81, my Ha flats are 21.67 seconds. and my S2 flats are 40.01 seconds.
Well Written Helpful