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Another BPM question  

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(@biggen)
White Dwarf Customer
Joined: 2 years ago
Posts: 17
March 1, 2020 22:01  

Just to clarify since the creation of the BPM in APP is full of confusion, if I want to create a BPM only, all I need are long darks and flats correct?  The flats can be any length/gain/iso/offset right? It doesn’t matter what filter those flats match? BPM just needs any flat?

Bias and flat darks should not be needed since I’m not creating a master flat, correct? I would uncheck “create masters” in this case.

And finally when the BPM is created it can be used for all data (e.g. different length subs, filters, gains, offsets, etc...)? It can be used universally for any sub coming out of that specific camera it was built for?

 

 

 

 

 


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3955
March 1, 2020 22:45  

It's not that confusing, you can simply select to create the BPM along with the calibration data you would normally already load in. So you add a good dark, a long one is preferred indeed and if your camera has any cold pixels, a nice flat. You can already make a BPM with just a long dark if you're sure your sensor doesn't show cold pixels.

The BPM can then be used for all situations in which that sensor is used yes.


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(@biggen)
White Dwarf Customer
Joined: 2 years ago
Posts: 17
March 1, 2020 23:10  

@vincent-mod

Ok, so the flat isn’t needed at all then if I’m not interested in cold pixels? Just a long dark?

The confusion arises since there are many tutorials all using different methods. Some use bias, some use flats, some use flat darks. The bottom line is that one ONLY needs long darks to create a BPM if you’re only interested in correcting for hot pixels. If you want to correct for cold, then flats are also needed.

I wouldn’t think cold pixel would be very common in newer CMOS cameras. I’ll probably just skip that and focus on hot pixels then.


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(@ippiu)
Red Giant Customer
Joined: 3 years ago
Posts: 90
March 2, 2020 13:51  

@biggen

@vincent-mod

I wonder if BPM can replace completely darks...so to avoid to use darks...what do you think?

I did a quick test (using some low quality frames from my asi533) and for me darks continue to be a better choice in the all process...but asi533 has no amp glow and so low read noise and almost no cold pixel...


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3955
March 2, 2020 15:24  
Posted by: @biggen

I wouldn’t think cold pixel would be very common in newer CMOS cameras. I’ll probably just skip that and focus on hot pixels then.

That's correct, cold pixels seem to be less of an issue, if at all, in the newer sensors. It never hurts to use a flat anyway though, just in case you miss one. But it won't have a huge impact.

Posted by: @ippiu

I wonder if BPM can replace completely darks...so to avoid to use darks...what do you think?

You can yes, however a Dark is also useful in the case where you have some amp-glow. If you have that, a darks is still necessary. Otherwise you can do without, though I always test that first by eye. If you find that adding darks gives a better result still, I would use both BPM and darks.

 

 


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