A word about color in black and white...

Although block and white films do not show colors, they have to record them. The first films made (or plates made, of course) were not color sensitive. They had no special sensitizers to extend the natural response of the silver salts, which is to blue light, into the rest of the visible range. They recorded green as slightly too dark, yellow slightly darker, orange and muddy grey and red as black.

This came to be called 'ordinary' sensitivity when the first extension of color recording ability arrived - ortho-chromatic film, which means 'straight' recording. In fact, ortho film was still almost entirely insensitive to orange and red - hence those dark, dark lips on the first black and white movies! They didn't really wear black lipstick!

In the early part of the 20th century, mono film was made more sensitive to orange and red, and this was called 'isochromatic' by some makers. That means 'equal'. But of course, it wasn't. You could still process it under a deep red safelight and it still made people look very pale, grass slightly dark and blue skies plain white.

Then, along with the Leica, came 'panchromatic' film - meaning 'all', or 'everything' sensitive. Agfa called their film Isopan just to rub the point in. Even so, panchromatic films were still much more sensitive to blue than any other color. You could however use yellow, orange, red and yellow-green filters on these (and with restrictions on isochromatic films) to shift the color sensitivity and thus the reproduction of blue skies in particular.

Those Ansel Adams prints with dark skies and white clouds are the result of panchromatic films used with an orange or red filter. Red produces the most dramatic effect, almost black sky on a summer day.

With Kodak T-Max and Ilford Delta (amongst others) we have started to see 'red pan' films. These are 'superpanchromatic', with new sensitizing agents making the emulsion record red light almost as well as it does any other color. This makes the film faster, and reduces any need for a filter to produce correct tones. It also tends to reduce contrast and makes the use of filters less effective, for a variety of reasons to do with the way film works.

Agfa's Scala reversal film is a film like this - it has extra speed, and extra sensitivity to red, does not need a filter to record a sky normally, and on the other hand does not react to the use of filters by displaying high contrast.

No-one bothers to write about color sensitivity in black and white films today, because no-one uses filters any more and really cares. However, I can tell you now that back in the 1970s when I used to shoot for national newspapers and magazines, my press-photographer rivals thought I was quite mad to use Ilford FP4 and an orange filter when they just loaded Tri-X and never used a filter in their lives. I wasn't. The difference between my shots and theirs was enough to secure national publication for dead ordinary little stories, things the local papers actually rejected as too parochial.

When did you last carry a set of filters with you to shoot black and white?