Originally posted by Joe Sullivan So I guess what you and others are saying is that with DSLRs, one cannot remove the blue scatter before it reaches the lens and therefore cannot use the haze-cutting properties of red filters, because the computer cannot deal with information it does not have and a hazy picture is a hazy picture. Is this correct?
I don't think that's quite right.
A few people upthread have mentioned the Bayer pattern -- each pixel on the sensor has a red, green, or blue filter over it, and the actual color image is reconstructed from that.
With your haze example, the blue/green components will be filtered out by your red screw-on filter, and pretty much equivalently by the red filters on the Bayer mask.
If you use the screw-on filter, you'll have an image reconstructed from red pixels and a whole bunch of blue and green pixels that don't receive much light and therefore don't contribute anything (because those colors were filtered out at the lens).
If you use software filtering and throw away the blue-green content, you'll have basically the same thing -- the red pixels will contribute to the final image, and the blue-green ones (where the haze is problematic) won't.
So you should be able to get rid of the haze pretty effectively in either case.
The screw-on red filter gives you the advantage of being able to see in the viewfinder what you're going to get on the sensor. Maybe you'll be able to get better critical focus without the haze in the way, with either manual or automatic focus.
In software, you can decide later if the virtual red filter is what you want, or if you want to do something different, or even keep the full color image. That's a big advantage for me.
A lot of people are comfortable these days (and I'm one of them) relying entirely on software color filtering. It's 99% as good as a screw-on color filter, if you're shooting in raw.
Unfortunately, there's no software substitute for a polarizer, so that's one to keep in your bag.
I think I'm saying basically the same thing selar and demp10 did, but I wanted to shed a little more light (ahem) on your haze question.