[Leica] Query re B&W photography in digital

[abridge at gmail.com (Adam Bridge)]

As I think about this I can imagine that there would be real benefits
from using a color filter on your lens.

Why?

Well, here goes.

By wanting to filter in the first place you're interested in a
particular range of optical frequencies. Everything else isn't content
you really want to capture and you wouldn't on black & white film.
Your digital sensor, of course, IS going to capture colors in RGB
regardless.

So, I'm thinking that for the purposes of exposure, and capturing the
best dynamic range, you should filter at the lens first and then use
photoshop to refine. You get the best capture from the camera because
you can set the sensor's sensitivity where it needs to be to get the
highlights but still get dark areas.

Using an infra-red filter is the prime example of this for the M8. You
want to cut everything but the IR so you do that in front of the lens.
Then in processing you can convert the image to luminance.

But suppose you use a blue filter - blue is often the noisiest of the
sensor's channels so if you filter the other colors you have a shot at
getting a better signal-noise ratio in the captured image.

I don't have many colored filters, only red, orange, and green I
think, so I can't test this one but I think it would be fun.

I could, of course, be totally and completely out to lunch. Many
people have suggested that to me! <grin>

Adam