Modulation transfer


A measure (or function) of a lens or a film’s ability to resolve fine detail. 1

There is often a need to indicate the contrast of the image relative to that of the subject, for all sizes of an image. The decline in image contrast with decreasing image size, caused by a film (or a lens, or any stage in the photographic process) can be investigated and shown as a curve representing the modulation transfer function (usually abbreviated to MTF).

The concept of modulation transfer is convenient for use in photography because the same method is used for evaluating other communication systems, such as radio and television, and in electronics.

Modulation transfer curve

A graph that describes a film’s capacity to reproduce complex spatial frequencies. The measurements indicate the effect on the image of light diffusion within the emulsion. MTF curves are used by photographers, research workers and engineers, when evaluating all or part of a photographic system.


Case, D., 1985, Motion Picture Film Processing, Media Manuals, Focal Press, London, Boston