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Flats and Darks for Flats acquisition using ASI AIR PLUS - Duration Matching

ZWO ASIAIR Plus Acquisition Calibration Dark Frames Deep Sky
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Dhiraj Patil avatar
Dhiraj Patil avatar
Hello

I have been using ASI AIR PLUS to collect FLATS and DARKS for FLATS  but when I load the data in PixInsights Weighted Batch Pre-Processing script, it is not using Darks for Flats to calibrate FLAT Images.

I am using PrimaLuce's GIOTTO Flat Field Generator at about 25-30% illumination.

When the FLATS were generated, the file name showed duration of 3.2 seconds. So I took DARKS for FLATS (with telescope lid) at 3.2 seconds.

However, WBPP did not use those DARKS for FLATS for FLATS Calibration. PIX INSIGHT's FITS HEADER shows FLATS were actually 3.15 seconds but somehow FILE name shows rounded figure of 3.2 seconds.

Could this be the reason why DARKS for FLATS at 3.2 seconds were not used for FLATS Calibration?

Should DARKS for FLATS duration match exactly as FLATS? . e.g in this case up to 2 decimal places? if yes, is there a way to find out this duration in ASI AIR PLUS's image management area or some other method?

Thanks

Dhiraj
DavesView avatar
DavesView avatar
My flats are always in the 8ms to 25ms range, depending on the filter and I use bias frames that exactly match the time duration of my flats. In WBPP, it does not show the correct time duration for the bias frames, but always shows mine as 0.00. Not sure why.
DanyJrt avatar
DanyJrt avatar
Have you considered shooting bias frames instead of dark flats ? It's way easier.
Jay Hovnanian avatar
Jay Hovnanian avatar
In WBPP, there is a setting - forgot what it is called, but it is very visible - that allows related frames to be matched within a set tolerance.  Even so ...

Each time I am out, I shoot only Flats.  At the end of each Lights session - I currently shoot only OSC, I go to the Preview screen, turn on the Histogram and set the exposure time to 3-seconds.  It doesn't take long to adjust the Flats Panel to achieve an ADU Average between 18,000 and 24,000.  If I am just over 24,000, I change the exposure to 2-seconds, which quickly gets the average into my desired range.  Then I switch back to the Autorun mode and shoot a desired number of Flats at either that predefined duration.

For each of my cameras, I keep reasonably current 2-second and 3-second Dark Flats in a Library. 

They always match up in WBPP, and an added visual benefit is that the file names are all clear and concise.

Perhaps this would help.
Helpful
polaco_cosmico avatar
polaco_cosmico avatar
It would be good to know the model of your camera that you use. In Asiair it takes my flats at around 32,000 to 34,000 adu when I do them automatically, but I use panel flats, I have them defined at 28,000 adu. greetings