Binning for Idiots

[Fordos Moon]

Those of you that have seen my posts before will know I am not a technical kinda guy, but a more enthusiastic learner you will not meet!

Looking at some fantastic images using CCD cameras I notice a lot of "binning" going on.

My questions are:

What is binning (using the 10,000 most widely used words in the English language only)?

How do you decide that binning is necessary?

When in the capturing and processing process does one bin?

Thanks as always

Bob

[hobsey]

Good question as I would also like to know.

[libraryman]

I will try, no doubt more knowledgeable posters will help.

Binningis simply the use of software to link/combine pixels (say 4 of them) to act as one pixel, thus you gain performance at the potential cost of resolution.

Binning...if it is available to you would be used as a tool for capturing data faster, I.e. when focusing perhaps or when needing to add colours to Luminance.

I'm not aware of the use of binning in processing applications

Ray

[PeterCPC]

Found this article - http://www.andor.com/learning-academy/ccd-binning-what-does-binning-mean

Peter

[ollypenrice]

Ray's is a good answer.

In terms of final images rather than handy grabbing of clearer, faster downloaded images for framing and focus I would say this:

1) Binning 2x2 gains signal at between 1.5 and 2x the speed of unbinned (bin 1) at a theoretical cost of resolution because your 2x2 binned 'superpixel' is 4x larger and can't separate fine detail.

2) Why 'theoretcially?' Because the 'seeing' (the stability of the lightpath to your chip through the atmosphere) may blur out your unbinned data so badly that it might as well have been captured in Bin 2 anyway. The seeing may not allow you to resolve at your Bin1 resolution so why bother trying?

3) If the seeing is marginal, so it just about allows you to resolve at Bin 1, you could shoot your luminance and Ha unbinned, where the resolution is worth having, but shoot your RGB binned 2x2 because the luminance will impose its finer resolution on the finished image.

So, how do you know what your sky will allow you to resolve? You experiment. Compare a binned and unbinned image after resizing the binned one upwards to the same dimensions as the unbinned one. If you are using small pixels at long focal length you are likely to find that you lose no resolution at all by binning. If you are using larger pixels at a short focal length then you'll find you lose a lot of resolution. The case for Bin1 luminance and Bin 2 RGB lies between the two. (I like to make my stars out of RGB only, without luminance, so I never bin colour 2x2 on my present rigs becaus I want small RGB stars, bot 'blocky' binned ones.)

Note that you cannot normally bin OSC cameras because the colour information would be destroyed. Also you'll sometimes read that binning 2X2 improves capture speed by 4x but measurement does not seem to bear this out.

Olly

[Fordos Moon]

Ray's is a good answer.

In terms of final images rather than handy grabbing of clearer, faster downloaded images for framing and focus I would say this:

1) Binning 2x2 gains signal at between 1.5 and 2x the speed of unbinned (bin 1) at a theoretical cost of resolution because your 2x2 binned 'superpixel' is 4x larger and can't separate fine detail.

2) Why 'theoretcially?' Because the 'seeing' (the stability of the lightpath to your chip through the atmosphere) may blur out your unbinned data so badly that it might as well have been captured in Bin 2 anyway. The seeing may not allow you to resolve at your Bin1 resolution so why bother trying?

3) If the seeing is marginal, so it just about allows you to resolve at Bin 1, you could shoot your luminance and Ha unbinned, where the resolution is worth having, but shoot your RGB binned 2x2 because the luminance will impose its finer resolution on the finished image.

So, how do you know what your sky will allow you to resolve? You experiment. Compare a binned and unbinned image after resizing the binned one upwards to the same dimensions as the unbinned one. If you are using small pixels at long focal length you are likely to find that you lose no resolution at all by binning. If you are using larger pixels at a short focal length then you'll find you lose a lot of resolution. The case for Bin1 luminance and Bin 2 RGB lies between the two. (I like to make my stars out of RGB only, without luminance, so I never bin colour 2x2 on my present rigs becaus I want small RGB stars, bot 'blocky' binned ones.)

Note that you cannot normally bin OSC cameras because the colour information would be destroyed. Also you'll sometimes read that binning 2X2 improves capture speed by 4x but measurement does not seem to bear this out.

Olly

Thanks Olly, it is atrting to make sense now! I look forward to an explanation in person next September if I haven't used it by then! (Still saving for CCD!)

[teleskopjo]

I think the best answer could come if a kind soul posts a binned vs. unbinned image

[lensman57]

You can only bin a Mono CCD camera, if you bin an OSC you will loose all the colour data. It is also not worth binning  a CCD with low pixel count. I have binned my 314L a couple of times with mixed results. Good cameras to bin if the FL is suitable are the ones with the KAF 8300 chip or an Atik 690.

A.G

[dph1nm]

You can only bin a Mono CCD camera, if you bin an OSC you will loose all the colour data.

There were some Kodak  OSC chips with fancy electronics which did allow true hardware binning (i.e.  produced a colour result) but I don't think I have never seen any images from any.

NIgelM

[lensman57]

There were some Kodak  OSC chips with fancy electronics which did allow true hardware binning (i.e.  produced a colour result) but I don't think I have never seen any images from any.

NIgelM

I think these were mostly with ultra high speed cameras and perhaps not suited to DSO imaging as the noise was terrible.

A.G

[Uranium235]

lensman57, on 24 Oct 2014 - 04:36 AM, said:lensman57, on 24 Oct 2014 - 04:36 AM, said:

You can only bin a Mono CCD camera, if you bin an OSC you will loose all the colour data. It is also not worth binning  a CCD with low pixel count. I have binned my 314L a couple of times with mixed results. Good cameras to bin if the FL is suitable are the ones with the KAF 8300 chip or an Atik 690.

A.G

I can vouch for the 8300 (383L+) in regard to binning. As long as your FL is not below 650mm, it can turn out some quite astonishing stuff when binned 2x2. Ive measured the gain on my camera multiple times - and 2x2bin always turns out to be 2.2x faster than 1x1.

The only downside is that the hot pixels are harder to get rid of, so you need a decent sub count for sigma clipping. But the end results are usually quite clean: