Another short comparison on binning. I completed this a while back as I am trying to decide whether binning is something I should be considering. Please remember that this is in no way scientific or comprehensive but designed to give me some kind of idea and thoughts on decision making.

Equipment
TSO RC 6inch Telescope
SW EQ6 R Pro Mount
ZWO 120mm Guide Cam
OAG
ZWO EAF
Pegasus Astro mini box
IDAS LPS D1 2" Light Pollution Filter

Dilemma, should I bin 2x2 or stay at 1x1. This occurred to me as I realised I was oversampled at 0.57 / pixel which  seems to me to way below what most skies would permit and then there is the guiding, and so any mechanical mount issues becoming more apparent. Not very rational but my feeling is that if I stay at BIN1 I would be able to take advantage of those times when everything syncs...…. but when would that ever be?

Looking at BIN2 imaging, I only see upsides, possibly better light gathering capability, less demands on guiding and the mount, shorter subs/integration time, better sampling...…. the downsides - bigger stars?

Why not test the idea?

Here we have two images for comparison of NGC 884 with similar integration times, same sub lengths and very similar sky conditions (sequences taken directly after each other), so there should be very little difference in sky quality. Both sets were integrated as normal with calibration frames, and then registered, normalised together, stretched and LP and banding removed (calibration not dialed in yet). Each image was analysed using Siril.

You can see from the BIN1 image that it is slightly dimmer, it has fewer stars, but the min/max FWHM is slighter lower than the BIN2 version. I do however notice a lot more noise in the BIN2 image. Information is in the annotations. Short and very simple result, conclusive possibly.

This simple result tells me that star size does not increase significantly and can be countered with shorter exposure times, the brighter image and therefore better light gathering capability may mean shorter integration time and the image scale would put me within the limits for guiding on my mount - fewer discards of subs.

One downside I do see from this simple test is the apparent noise in the BIN2 image, something I think I can deal with or live with.

I do hear arguments around CMOS/CCD Hardware/Digital binning being something that is different and in the past the binning on the CCD was better but I don't own a CCD so cannot compare.

A better test would be to have longer sub times and integration time.

Anyway after these results I don't really see a reason not to try binning 2x2. Would really love some thoughts and experiences on this.

Lastly, looking at my data that hasn't really seen much post processing is more appealing on my eye, maybe I am too hard with PP work, something to think about for the future.

Thanks Brad