Binning; What is it?

[Redscouse]

Hi all 

Yet another question, well three really.
I noticed a setting in APT last night that said 'binning' and gave me the options of 1x1 or 2x2.
Can I ask what is binning, what setting do I need, and why?

Thanks for looking.
Pete.

[JemC]

I think you may find this link of interest, 

https://www.swagastro.com/to-bin-or-not-to-bin.html

[Redscouse]

6 minutes ago, JemC said:

I think you may find this link of interest, 

https://www.swagastro.com/to-bin-or-not-to-bin.html

Thanks for the link JemC. Very informative and surprisingly easy to read/understand. 

[wimvb]

Great read, indeed. Binning is of use if you have a ccd. But if you use a cmos/dslr, it's not as straight forward. This is because of the way the data is read from the sensor.

[kens]

It's a little more complicated now with CMOS cameras. With CCD cameras binning works by combining the charge on the binned pixels before they are read so at 2x2 you get 4x the signal but only 1x the read noise. CMOS cameras cannot do this so the pixels are only combined after read noise has already been added. This matters because the dynamic range of the camera is determined by the well depth divided by read noise. So with CMOS the recommendation is to not bin or to do so in post processing only as there is a SNR advantage. The only other advantage is a reduction in file size.

[Redscouse]

After reading the link JemC pointed me towards, what you two have said makes perfect sense.
Thanks all.