Binning a Mono

[AstroRuz]

Hey all,

So tonight I might try binning my mono camera for the first time. Since I have extremely limited time. 

From what I understand, people bin their RGB channels as it's just the colour data that's needed. Then add a 1x1 image of the Lum channel over it to create the actual detail. Hence the entire point of using a lum filter. So from what I can gather the 2x2 RGB images (even though they're slightly undersampled) won't be too bad as I just want as much signal as I can get and they'll still be native resolution of 5496*3672 with the ASI 183mm Pro. They'll just be 4.2um pixels instead.

Am I understanding this correctly?

Many thanks,

Ruzeen

[carastro]

Almost right.  But the binned images will be half the size of the Luminance images, so you will need software that will re-size them. 

What software are you using for stacking and processing?

Carole 

[AstroRuz]

Just now, carastro said:

Almost right.  But the binned images will be half the size of the Luminance images, so you will need software that will re-size them. 

What software are you using for stacking and processing?

Carole 

Ah right so they will be 2748 x 1836 pixels then? Makes sense I suppose pixels twice the size, half the resolution then.

I'll probably be drizzling them 2x with DeepSkyStacker, although I have access to AstroPixel Processor as well as PixInsight which I have a trial for and no idea how to really use 😛

[carastro]

Pretty sure APP will re-size them (never used it).  Pixinsight definitely does.

I bin all the time but use different software.

Carole 

PS: Love the name 

Quote

AstroFarsography

 

Edited March 5, 2021 by carastro

[AstroRuz]

Just now, carastro said:

Pretty sure APP will re-size them (never used it).  Pixinsight definitely does.

I bin all the time but use different software.

Carole 

Excellent. So then I gather aside from the image resizing. If I bin 2x2 RGB I get a greater SnR (at the expense of resolution), and then putting a 1x1 Lum layer over the top to actually bring out the details is the correct way to go?

Thanks. I feel more informed going into this evening now  

[carastro]

That's right so you can actually do a 600sec exposure in 300sec if binned x 2.

Yes at the expense of resolution, but as you say it is really just the colour aspect (on most images), so the unbinned luminance puts in the detail. 

I do the same with narrowband, Oiii and Sii get binned but Ha doesn't. 

Speeds up imaging time and means I can get the full data for an image quicker.  

Carole   

Edited March 5, 2021 by carastro

[AstroRuz]

5 minutes ago, carastro said:

 

PS: Love the name 

 

Thank you. I thought I was being clever, but it turns out it's quite tricky to pronounce for a lot of people 😅

[carastro]

I think it must be 2014 when I last did Oiii Sii and RGB unbinned.  

Carole 

[AstroRuz]

Just now, carastro said:

That's right so you can actually do a 600sec exposure in 300sec if binned x 2.

Yes at the expense of resolution, but as you say it is really just the colour aspect (on most images), so the unbinned luminance pus in the detail. 

I do the same with narrowband, Oiii and Sii get binned but Ha doesn't. 

Speeds up imaging time and means I can get the full data for an image quicker.  

Carole   

Awesome.

My plan is to use the ASI 183mm Pro on the Evostar 80ED (possibly without the reducer) on M81 & M82. Was going to bin my RGB and not the lum data to try and get a nice image from it. I thought about how you'd bin narrowband also but I guess that makes a lot of sense since emissions are mostly Ha so using Ha as the lum certainly makes a great deal of sense. I'll go forward with this suggestion I think! Certainly makes mono that much more appealing and/or justified with our British skies

Thank you  

[carastro]

I use a CCD camera, but am pretty sure the same principals apply to CMOS cameras, but obviously your unbinned capture length might be a lot shorter than mine and thus the binned even shorter still.  

Carole 

[MartinB]

Hi Ruzeen.

I have moved your post onto this board, hope you don't mind but this is for imaging topics to be discussed whereas the other is the place to post your images.

Binning can help for 2 reasons.  Gradually becoming less relevant but which used to be the most important reason is that binning CCD cameras gives a 4 fold reduction in read noise.  This has massive benefits in that it reduces minimum exposure time required by a factor of 4 whilst increasing dynamic range.  However, with CMOS cameras like yours the chip is read in its entirety rather than pixel by pixel so this benefit is lost.  However, read noise is generally lower with CMOS chips than CCDs so this is less relevant anyway.  You can still benefit from binning CMOS cameras since the 4 combined pixels will have been averaged out which will work in a similar way to stacking pixels, so, improved SNR.  This means that you can still reduce your overall exposure time.

For the most part, detail is provided by the luminence channel.  The colour image doesn't need to be high resolution.  Just be aware that some people aren't keen on binning since they find their stars become a little bloated.  This is dependent upon factors such as pixel size and focal length being used.  Also it tends to be much more of an issue with broadband  than with narrow band.

[Stuart1971]

32 minutes ago, AstroRuz said:

Thank you. I thought I was being clever, but it turns out it's quite tricky to pronounce for a lot of people 😅

Also FYI if it’s a CMOS camera the binning is only done at the camera software level, whereas with CCD cameras you can do true hardware binning, I am not sure what difference this makes, but it does make one...👍🏼

[AstroRuz]

25 minutes ago, MartinB said:

Hi Ruzeen.

I have moved your post onto this board, hope you don't mind but this is for imaging topics to be discussed whereas the other is the place to post your images.

Binning can help for 2 reasons.  Gradually becoming less relevant but which used to be the most important reason is that binning CCD cameras gives a 4 fold reduction in read noise.  This has massive benefits in that it reduces minimum exposure time required by a factor of 4 whilst increasing dynamic range.  However, with CMOS cameras like yours the chip is read in its entirety rather than pixel by pixel so this benefit is lost.  However, read noise is generally lower with CMOS chips than CCDs so this is less relevant anyway.  You can still benefit from binning CMOS cameras since the 4 combined pixels will have been averaged out which will work in a similar way to stacking pixels, so, improved SNR.  This means that you can still reduce your overall exposure time.

For the most part, detail is provided by the luminence channel.  The colour image doesn't need to be high resolution.  Just be aware that some people aren't keen on binning since they find their stars become a little bloated.  This is dependent upon factors such as pixel size and focal length being used.  Also it tends to be much more of an issue with broadband  than with narrow band.

Thanks Martin that's fine.

Hmm so by the sounds of it then with the ASI183 being what I guess is a relatively modern-ish camera then it falls under the diminishing returns category then as you say, it's less relevant these days. So maybe I will just keep it 1x1 and not have to worry about loss of resolution. I intend on possibly printing anyway so I want all the resolution I can really.

Bloating stars is always an aggrievance. I know how to deal with it, but prevention is better than cure after all.

Many thanks!

13 minutes ago, Stuart1971 said:

Also FYI if it’s a CMOS camera the binning is only done at the camera software level, whereas with CCD cameras you can do true hardware binning, I am not sure what difference this makes, but it does make one...👍🏼

Yeah I've heard that being thrown around. I'm not sure either but I  guess it's like imitating rather than being the real thing perhaps.  

[Clarkey]

FWIW I have tried binning my ASI1600MM both in the camera and in software afterwards and I struggled to see any significant difference. Similarly using un-binned made very little difference to the image quality. Obviously, as the ZWO CMOS cameras average the 4 pixels when binning 2x2 there is no real advantage in 'speed'. It is a shame that they do not 'sum' the pixels in the camera - that would give a significant increase in data capture rate. Given the very low read noise of a CMOS sensor I have never really understood why this is not done? Perhaps someone more knowledgeable than me could explain....

[CraigT82]

You would prob be better off just collecting the data as normal and then binning the colour channels yourself in software later (pipp is pretty good for this) you can set the binning method , average/sum and it should approximate the same benifits you get from hardware binning a CCD. I've binned lucky imaging data from my 290mono like this before with decent results 

Edited March 5, 2021 by CraigT82

[david_taurus83]

I had a go at binning the ASI1600 on camera versus in software. Software was better.

https://stargazerslounge.com/topic/342762-software-binning-explained/

[Clarkey]

1 hour ago, CraigT82 said:

You would prob be better off just collecting the data as normal and then binning the colour channels yourself in software later (pipp is pretty good for this) you can set the binning method , average/sum and it should approximate the same benifits you get from hardware binning a CCD. I've binned lucky imaging data from my 290mono like this before with decent results 

I have done the binning in software for each channel as you suggest, but not using PIPP. (I have downloaded it for trying planetry imaging at some point in the future but not used it yet). If it has a 'summing' function I might try it out. Affinity uses a number of algorithms but I could not see a huge reduction in noise.

Thanks.

[CraigT82]

7 minutes ago, Clarkey said:

I have done the binning in software for each channel as you suggest, but not using PIPP. (I have downloaded it for trying planetry imaging at some point in the future but not used it yet). If it has a 'summing' function I might try it out. Affinity uses a number of algorithms but I could not see a huge reduction in noise.

Thanks.

Yes you can definitely set it to either average or sum in pipp, and you can load up and output fits files too. I just need to caveat this by saying I haven't tried it with deep sky images, but I was very pleased with the SNR boost using the sum method when I was trying to lucky image the minor components of the trapezium with my 290m recently. 

[Clarkey]

No harm in giving it a go. I'm not sure, but it looks like it might only give an 8 bit output.

[CraigT82]

If you select tif or fits as the output file it will give you 16 bit images.

[Clarkey]

Thanks - I'll definitely give it a go with some noisy data and see what happens.

[Hals]

Just to be clear,  would simply resizing the 2x2 binned image to the same size as 1x1 in PS be ok?

Or would I need something more exotic like APP\PixInsight?