black-and-white film

Black-and-white film in photography utilizes a sensitive surface composed of gelatin containing minute suspended silver halide crystals, typically silver bromide with some silver iodide. When exposed to light in a camera, these crystals form an invisible latent image that can be developed into metallic silver.1

Key characteristics of black-and-white film that interest photographers include graininess, resolving power, and contrast. Graininess, most noticeable in large enlargements, is more prominent with faster films that have larger silver halide crystals. Contrast refers to how well the film reproduces tone differences in the subject as density differences in the image. This is often expressed by a measure called gamma, where a steeper slope on a characteristic curve indicates higher contrast.23

Roll film, commonly used in cameras, is wound on a spool with a light-tight backing paper to protect it.4