As stated previously, when a photographic emulsion is exposed to light, there is an invisible change produced in the minute crystals of silver halides that results in a latent image. To make the image visible, you must treat the exposed emulsion in a solution known as a developer. This solution converts the halides affected by light to black metallic silver. These black metallic silver particles form the visible image on the negative.

At the beginning of development, there is little difference in density between the highlight and shadow areas of the film. However, during normal development, this difference increases because the highlight densities continue to increase after the shadow areas are completely developed. Development should stop when the contrast between the shadows and highlights reaches a desired difference. The activity of the developer, and to some extent the type of film, primarily determines this developing action.

One type of developer cannot cover all situations; for example, film exposed by poor lighting conditions may require an active developer to bring out as much of the image as possible, while a film exposed under normal conditions requires a normal working developer. There are many different developers, each provides different activity and quality of development. The actual choice of the developer to use depends on the type of film, conditions under which it was exposed, type of negative required, and the developing time that is best for your development method.

GENERAL-PURPOSE DEVELOPERS

A developer for general-purpose work should produce moderate grain, normal contrast images. Clear areas of the negative, as well as the image areas, should be basically fog free.

Some general-purpose developers are as follows:

HC-110

DK-50

Microdol