Langford's Basic Photography, 10th Edition

Appendix C: Expressing Film Response

Film response to light is often presented in manufacturers' technical data in graph and in table form. Both allow you to make comparisons between different products, show a film's performance under differing conditions, etc. It is therefore worth making yourself familiar with how certain technical information is expressed, and what this means in practice.

Response to color

A graph such as that in Figure C.1 (top) shows how a particular black and white film responds to the colors of the visual spectrum, on the final print. This film records deep blues and purples, and to a lesser extent reds, as lighter in tone than they appear to the eye. On the other hand, it responds to greens as if darker than the eye's ...