There are two modes for binning a ZWO OSC camera. One is the default of "Color-binning" and the other is "Mono-binning". Both are done in the device driver rather than on sensor / in-camera (I think).They give different results and can be used for different purposes. There was a recent thread where the modes were discussed. I made a long post there about the "resolution" aspects related to Color-Binning in the driver versus doing a similar operation later in post-processing. Check out the whole thread for other views.
If I wish to employ binning for an image, I do it in post-processing. However, I choose to set the Mono-Binning flag in the ASCOM driver. This means that I always shoot at 1x1 binning for imaging. However, I use 2x2 for plate solving and focusing under SGP. This results in the downloaded image being monochrome and gives me more consistent results (because of the lack of the CFA matrix pixilation effects). For framing, I use 3x3 (mono) binning for the faster frame rates.
I was hoping you would chime in. Interesting post you link to. Actually, I'm surprised that the biggest deterrent is the sampling loss with binning OSC. That to me is very interesting and while obvious in hindsight was not something I was considering. This I suppose leads to another consideration. I'm planning to use my OSC camera to sample color data and my mono camera to sample luminance at a higher resolution.
So, at what point is color data undersampled for the luminance data it is intended to be used with? In the "old" days with CCD (and the current days for people who realize these cameras are still relevant) we would bin1 for lum and bin2 with color. This seemed to work and not "confuse" color association when combined with the higher resolution mono.
In my case, I would be imaging mono at 1.78"/px on one scope, and then on another scope the color data would natively be 1.59"/px or if I binned 2 (using the 1/3 less sampling consideration you outline) I would be at 4.77"/px. (which correct me if I am wrong is like binning 3x with mono bin)
That would have luminance data at about 2.7x the resolution of the color data if I binned the OSC. Maybe this would be fine enough sampling on color data, but I would worry about bleed of color when applied to the luminance.
Edited by ChrisWhite, 23 October 2021 - 10:58 AM.