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DSLR data calibration without darks  

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(@hanva)
Hydrogen Atom Customer
Joined: 3 years ago
Posts: 1
February 22, 2018 18:43  

Hi.

Iam a newbie with APP. How can I calibrate a dslr data without darks? I have been watching tutorials, but I dont understand the workflow.


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(@mabula-admin)
Quasar Admin
Joined: 4 years ago
Posts: 2486
March 10, 2018 17:37  

Hi @hanva,

Thank you for your question and welcome to the APP forum. My apologies for the delay in my response.

If you want to calibrate DSLR data without darks, you will need to use at least a masterbias if you are using flats as well. Are you?

(The hotpixels can be taken care of most efficiently by making a one-time BPM from a simple set of darks.)

Kind regards,

Mabula

 


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(@gregwrca)
Neutron Star Customer
Joined: 3 years ago
Posts: 227
March 10, 2018 23:38  

I had a couple of occasions where I had to throw out my bias in order to integrate my hydrogen Alpha Subs. When I included it I got blank frame when I pulled it out of the mix I got it really nice image in hydrogen Alpha


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(@mabula-admin)
Quasar Admin
Joined: 4 years ago
Posts: 2486
April 5, 2018 21:53  

Hi Greg, Probably a case of subtracting the bias pedestal twice then 😉

Next APP version 1.060 will not have that problem anymore...

Mabula


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(@gregwrca)
Neutron Star Customer
Joined: 3 years ago
Posts: 227
April 5, 2018 21:56  

Great. And yes, I'm sure that's what happened.


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(@infinite_wisdom)
White Dwarf Customer
Joined: 1 year ago
Posts: 15
February 1, 2020 15:58  

So, can someone please clarify the exact workflow of DSLR calibration without darks?

I normally calibrate with darks, flats, bias and bpm. Do I just leave the darks selection empty, or load my bias in there?

Also, do i have to dither? And which checkboxes do I need to select?

Cheers 

 

 


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(@vincent-mod)
Universe Admin
Joined: 3 years ago
Posts: 2684
February 5, 2020 15:43  

Ok a number of questions here, some general advice;

- Always use darks when you have amp-glow, if not and you still want to remove bad-pixels, you will need at least a BPM (Bad Pixel Map) and you can leave the darks empty.
- Dithering is always advised as it removes any fixed pattern noise that might still be present and will therefore always improve your result. If you're under-sampling, dithering is even required to perform drizzling if you want that.

Dithering is done during the taking of photo's, no checkboxes needed in APP.


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(@infinite_wisdom)
White Dwarf Customer
Joined: 1 year ago
Posts: 15
February 5, 2020 20:29  

Ah, ok.

I have dithered in the past, but stopped recently due to mount backlash issues.

Thanks for the clarification. 


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(@vincent-mod)
Universe Admin
Joined: 3 years ago
Posts: 2684
February 5, 2020 20:51  

Ah yes, backlash is fun isn't it. I wanted all of this to work nicely each time, so I even took apart my AZ-EQ6 and relubricated everything + changed some components. Got a nice feeling out of that for finetuning such a mount which is nice. It makes dithering and proper guiding work at least more stable. Good luck with it!


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