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Binning RGB at 2x2 with 1x1 L channel?

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#1 ryanha

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Posted 25 October 2020 - 11:04 AM

I have a trip planned to a dark site coming up in a couple weeks and want to plan out what I am going to do.

 

I have read that some people use 2x2 binning on the RGB filters and 1x1 on the L filter.

 

Does anyone have any pointers to reading materials on when this is appropriate and any other related details?

 

I am imaging with a C8 + F/6.3 reducer (1280mm), with ASI294mm mono camera + Baader LRGB filters

 

Thanks,

--Ryan



#2 choward94002

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Posted 25 October 2020 - 11:42 AM

John Rista would be your go to person for asking about binning ... I would PM him but understand that binning on a CMOS is different than binning on a CCD.  With a CCD you're creating a "super pixel" which gives more read depth and dynamic range [https://andor.oxinst...cle/ccd-binning].  With CMOS binning simply does an add of the pixels without changing the read noise [https://astronomy-imaging-camera.com/tutorials/everything-you-need-to-know-about-astrophotography-pixel-binning-the-fundamentals.html].  Your camera is a CMOS but you may be thinking about binning as if you've got a CCD ...

 

What that means is that suppose you are going to saturate after 10min with a single 1x1 pixel.  If you bin on a CCD you've now decreased the read noise for that "super pixel" which means that it will now saturate after 15min, increasing the dynamic range available at the expense of detail.  If I bin on a CMOS, however, each pixel will still saturate after 10min, it's just that I will have more "signal" from those four pixels.

 

The articles I linked are a good start, posting to John Rista or the other experts who will reply to this is a good second ...


Edited by choward94002, 25 October 2020 - 11:43 AM.


#3 Madratter

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Posted 25 October 2020 - 11:44 AM

There is little point to binning almost all CMOS cameras in camera other than saving disk space and download time. Those strategies made sense mostly for some CCD cameras.


Edited by Madratter, 25 October 2020 - 01:47 PM.


#4 bobzeq25

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Posted 25 October 2020 - 12:14 PM

I have a trip planned to a dark site coming up in a couple weeks and want to plan out what I am going to do.

 

I have read that some people use 2x2 binning on the RGB filters and 1x1 on the L filter.

 

Does anyone have any pointers to reading materials on when this is appropriate and any other related details?

 

I am imaging with a C8 + F/6.3 reducer (1280mm), with ASI294mm mono camera + Baader LRGB filters

 

Thanks,

--Ryan

Binning color seems to go in and out of fashion.  With your image scale it makes a whole lot of sense.  I've done imaging with it, and without it.

 

Madratters point is that you need not bin CMOS in hardware when you image.  You can just resample your data in processing.  For CMOS those things are equivalent, mostly.  You don't get the read noise benefit with CMOS that you do with CCDs, but you still get the more important improvement in signal to noise ratio by binning (or resampling) 2X2.

 

The theory is that you can use lower resolution for RGB data in LRGB imaging.  Because your eyes see detail in the L, not the RGB.  You're basically just painting the L with RGB.

 

Some people like doing it, some not.  Give it a try, see what you think.  You can do it by resampling in processing, that's readily reversible.


Edited by bobzeq25, 25 October 2020 - 12:14 PM.


#5 ryanha

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Posted 25 October 2020 - 01:18 PM

Ok, and is the rule of thumb correct that I should do 50% of my total imaging time in L and the other 50% split evenly between R G and B?

#6 bobzeq25

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Posted 25 October 2020 - 01:28 PM

Ok, and is the rule of thumb correct that I should do 50% of my total imaging time in L and the other 50% split evenly between R G and B?

It's more than "good enough", though some vary. In particular you can get away with less RGB if you bin.  But that's an advanced technique, I recommend you take your stated approach.


Edited by bobzeq25, 25 October 2020 - 01:29 PM.



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