"Wilba" wrote in message
...
that you have more options working with the source
(the light in the scene), than you do working with a derivative image.

How so?
(polarising filters excepted)

You talkin' to me? :-) I'll have a go, but I don't really know what I'm
talking about.

OK, I will accept that disclaimer.

It makes sense to me via the general principle that the closer you get to
the source of any signal, and the fewer times you transform it, the
greater
the fidelity.

So adding glass filters is less harmful than manipulating pixels in your
opinion?
I doubt many would agree with you, and certainly not with any proof.


In my limited experience, trying to enhance the contrast between clouds
and
sky via the channel mixer can only go so far - eventually I start to get
visible artefacts, posterisation(?), whatever it is.

Well a polarising filter is often the best choice there.


Yes, I know that there are many other ways to get B&W, and that it's
different with RAW, bla bla bla, but when I hit that limit, I'd like to
have
more contrast in the original image to start with.
Does that make sense to you? :-)

No, but feel free to do whatever suits you regardless :-)

MrT.