While we sit 'ere chatting over a hot cuppa, I'll pass round a picture I took toady taking advantage of a 'fog filter' to let me snap the sun.
Not enough detail to stack automatically, so these are done manually – the technique is simple: Paste an image over the first one and set its transparency to 50%, then line it up.
Before combining all the images the transparency (starting from the bottom) has to be set to 100/n (i.e. 100, 50, 33, 25…) so each image contributes the same amount to the final result. After 26 frames it is a bit mind-numbing.
Naturally a touch of sharpening and tweaking of the levels/colour for the final result. You shoudl be able to see three 'active regions'.