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Mixed gains?  

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(@oopfan)
Main Sequence Star Customer
Joined: 8 months ago
Posts: 37
March 19, 2019 13:52  

I got a thumbs up from a respected friend on this topic. I'd like to run this by Mabula before investing in a new project:

I am planning on imaging in HaLRGB for the first time. I have a CMOS camera and normally use Gain 200 for LRGB since it gives me low read noise and great dynamic range to avoid saturation of the brightest stars. The only drawback is a moderate amount of quantization at 1.74 e-/ADU. But when I make monochrome-only images in narrowband I double the gain to 0.89 e-/ADU to give me unity gain allowing for the effects of quantum efficiency.

My question is: "Can I mix gains like this?"

Thanks you,

Brian

This topic was modified 6 months ago by Mabula Haverkamp - Admin

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(@mabula-admin)
Quasar Admin
Joined: 2 years ago
Posts: 2128
March 19, 2019 23:03  

Hi Brain @oopfan,

Sure, no problem ๐Ÿ˜‰

But since you use a CMOS camera, you might have some amp-glow on the longer exposures, right?

I would advise you to make matching calibration frames for the different gain values. APP will automatically match the lights with the correct masters based on the gain values.

Mixing gain values should not be a problem, just realize that with different gain values, you need to create more calibration frames to do it properly ๐Ÿ˜‰

Let me know if this is clear,

Kind regards,

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@oopfan)
Main Sequence Star Customer
Joined: 8 months ago
Posts: 37
March 19, 2019 23:09  

Yes, very familiar with calibration frames. So, no other concerns? Multipliers, etc. I find that APP runs well with default settings. I was just wondering if mixing gains meant that defaults no longer apply to one degree or another.

Brian


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(@mabula-admin)
Quasar Admin
Joined: 2 years ago
Posts: 2128
March 19, 2019 23:48  
Posted by: oopfan

Yes, very familiar with calibration frames. So, no other concerns? Multipliers, etc. I find that APP runs well with default settings. I was just wondering if mixing gains meant that defaults no longer apply to one degree or another.

Brian

Hi @oopfan,

No ๐Ÿ˜‰ not really, just take care of providing APP the necessary calibration frames.

The defaults should still give a very good result. A setting which you probably can adjust to improve things is using multiply-scale in 5) normalize ;-), that should help with improving data normalization.

Let me know how things work out with your new project ๐Ÿ˜‰

Mabula

ย 

Main developer of Astro Pixel Processor and owner of Aries Productions


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