It's complete wizardry I think The Olympus stores a raw and jpeg for each image taken and then does a bit of magic and comes up with a jpeg that is a stacked image - in camera. So, so clever! I think it stacks the jpegs, but by the sounds of it, with Affinity I could go back and stack the raw files which would give a bit more control.I don't have a camera capable of stacking, so I'm not sure how it actually works. Multiple layers of exposures perhaps?
I may have more control, doing it manually so to speak, but then again, camera's are pretty damned clever these days..