Thanks Robin,
That's a great explanation - I think I really get it now. Being a bit of a geek, I really feel I need to understand the underlying mechanism.
To that end, I've been running a few experiments here.
These are all graphs made from the histogram SharpCap outputs. All are 1ms darks.
The first image shows the effect of just changing the offset (aka brightness). The Gaussian distributions are clearly centred approximately around the offset setting.
The second image shows the effect of gain when the offset is constant. As you explained, the higher gain causes the distribution to spread out. In each case, the area under the curves will be the same, corresponding to my 16,000 pixels.
The third image shows the effect of even greater gain with constant offset. In this case the offset is now clearly insufficient and demonstrates why the offset should be increased with gain.
I suppose you could just set an offset big enough for all circumstances? I'll have to explore the downside of that.
Many thanks
Steve

- 1ms_G90_Off40+80.PNG (42.87 KiB) Viewed 1092 times

- 1ms_G90+150_Off40.PNG (39.59 KiB) Viewed 1092 times

- 1ms_G90+250_Off40.PNG (39.32 KiB) Viewed 1092 times