[yusuf]

No, PP should do. I feel Digital has retired most filters except CP & ND.

[georgweb]

We have discussed red channel clipping before. You can reduce it either by dialing down saturation before taking the pic or use the already mentioned light blue filter in front of your lens.

Here's two examples:
Red flowers in the sun: You can see with your bare eyes that the reds are melting to a shapeless blotch.
The dreaded reddish lights on small stages: Same thing happens with people's faces.

On both accounts the reds are clearly over the top. PP can't help. Gotta dial down the reds in-camera (or color saturation as a whole) before exposure. Or use that light blue filter.

I think there is a misunderstanding in the use of dynamic range which is likewise to the misunderstanding in depth of field. What I mean is the idea that you have a bracket of 1.0 valued correct exposure or in-focus throughout, bounded by a 0.0 valued zone on both sides.

[Class A]

Gotta dial down the reds in-camera (or color saturation as a whole) before exposure. Or use that light blue filter.

Or dial down exposure as a whole. As I said this will increase noise in the other channels but it is a possible solution.

[v5planet]

You can emulate colour filters in post-processing but some may still want to use the real filters. A real filter (e.g., for incandescent light) can help to avoid clipping in a colour channel. You can achieve the same by using exposure compensation but then you are introducing noise into the channels that did need to be attenuated.

Normally, however, this is completely irrelevant -- in particular with cameras with a fantastic DR like the K-5 -- so in practice one doesn't really need colour filters in front of the lens anymore.

I've noticed this in a lot of my B&W conversions on color photos taken with the K-7. Often the most interesting conversions result in some pretty serious and hideous banding that's hard to get rid of.

I imagine real deal screw-in color filters would expose properly on the channels you were interested in, without over-exposing the ones you weren't. Still, unless you really knew what you were going for, I feel like it'd be worth the hassle of farting around with PP later and clean it up as best you can, instead.

[jcool]

I use a PL filter more than not and really enjoy IR feature on K20d but also use Hoya filter on occasion and results are better