[DavidTrap (David)]

I'm just after clarification.

When I've been reading imaging threads, I have the impression some have processed their long (eg. 600sec) and short (eg 30sec) subs, by combining all of these subs into the one group with the expectation that this will bring back detail in over / underexposed areas..

If you were doing a median combine (or similar), this makes no mathematical sense to me - it would still give you the middle value of the pixel from a group of "bright" and "dark" subs.

I thought you had to process subs of equal length in separate groups and then combine them in Photoshop with layers & masks.

Is there some mathematical process where it would work to combine different length subs

ta in advance,

DT

Edit - this query applies to DSLR images only - I have no idea about monochrome LRGB imaging...