What does "bin" mean ?

[kirkster501]

Been reading abut CCD's - regrettably not for me just yet - and I see 1x1 and 2x2 "binning" ? What's all that about please? Don't even know what to search for to work it out....!

Thanks, Steve

[Freddie]

1x1 is where every pixel acts individually, 2x2 is where a square group of pixels two wide by two deep are made to act as a single larger pixel, same with 3x3 (three wide, three deep) etc etc etc Larger pixel more sensitive, hence allowing reduced exposure time, but obviously lower resolution.

[DoctorD]

Hi

Binning is the act of combining data from more than one pixel to improve signal to noise in return for lower resolution.

http://www.pco.de/fileadmin/user_upload/db/download/pco_cooKe_kb_binning_0502.pdf

HTH

Paul

[kirkster501]

OK thanks for that guys. So do you configure what "binning" you want in the camera control software on a per exposure basis? Would the binning method used have to match between lights, flats, darks etc ? And what determines the binning you want? seeing? subject?

[Freddie]

Yes, you set the binning in the capture software. Tends to be used with the R,G and B colour captures for LRGB imaging as the resolution isn't critical for the RGB and binning reduces the exposure time needed for each capture. Does need to be the same for the calibration shots.

[ollypenrice]

You also need to redo your flats in binned mode. You can get away with resizing unbinned flats but it's better no to. You also need to used binned bias frames to calibrate binned flats. Binned darks are also needed.

The boost in sensitivity is between 1.5 and 2x. The cost in terms of quality depends on your sampling rate. As a rule of thumb don't bin at very short focal lengths.

Very large, long FL scopes will often be binned for everything including luminance because the sampling rate unbinned is trying to resolve below what the atmospheric seeing allows. This is a waste of time.

Olly

[dph1nm]

Binning only has a real effect if your 1x1 pixels are read-noise limited. Then there is a signal-to-noise advantage in binning the CCD 2x2 or 3x3 etc. Otherwise you can just as well combine the pixels in software as on the chip - the effect is pretty much the same.

NigelM

[r3i]

Binning is also handy with larger chip cameras to reduce the image download time from the camera to the computer when you're performing the 'frame and focus' routine prior to doing the full image capture. It enables the image to be quickly refreshed on the computer.

Also most colour cameras if binned will not be able to produce a colour image as the individual RGB pixels in the bayer matrix get merged. I say most because I'm sure I saw a colour camera advertised that it could produce a colour image even after binning.

[Gina]

I find binning very useful when framing a DSO with my Atik 314L+ mono camera. I can use a much shorter exposure looping while moving the mount with EQMOD/ASCOM to position the image withing the frame.

[kirkster501]

hmmm, interesting. i need to read more about it me thinks. Still don't fully get the details - but I gt the idea now. Thanks.

[dph1nm]

I say most because I'm sure I saw a colour camera advertised that it could produce a colour image even after binning.

Yes, there were certainly some Kodak colour CCDs which could be on-chip binned correctly. The KAI-10100 for one.

NIgelM

[ollypenrice]

For fast dowload and faster previews of faint objects, yes, bin like crazy!

Olly

[Gina]

Yep, I bin 8x8 (the maximum) for finding and framing faint objects.

[r3i]

Yes, there were certainly some Kodak colour CCDs which could be on-chip binned correctly. The KAI-10100 for one.

NIgelM

This was the one that I came across: http://www.opticstar.com/Run/Astronomy/Astro-Imagers-Opticstar.asp?p=0_10_0_50_250