An enlarger is a darkroom tool which projects images from negatives onto enlarging paper for the purpose of making prints. Enlargers are usually an integral part of the film photography process, unless photographers are making contact prints, which are produced through a different process. Therefore, it is common to see an enlarger, or several, in the darkroom environment. Photography supply companies carry an assortment of enlargers, which can get quite costly when they are highly specialized.
To use an enlarger, the photographer mounts film or a glass negative in a special holder on the enlarger, which projects light through the negative. Usually, the enlarger points down at a flat surface which is designed to accommodate enlarging paper. The photographer can adjust the focus of the enlarger, as well as the size of the resulting enlargement. There is also usually room for a filter which can be used to change the quality of the light reaching the negative for specific desired effects.
After the enlarger has been focused and adjusted as needed, the photographer takes a sheet of enlarging paper and mounts it underneath the enlarger. If cropping is desired, metal strips can be used to adjust the amount of paper exposed. The enlarger is turned on again the expose the image for the desired length of time before being shut off to stop the exposure. Often several test runs are required before the desired length of exposure is reached, and many photographers start by making a test strip with varying lengths of exposure to determine how long the enlarging paper should be exposed.
Next, the enlarging paper is run through a developer to bring out the exposure, a stop bath to halt the actions of the developer, and a fixer to fix the image onto the paper. Finally, a rinse with water ensures that the developing chemicals are removed, so that the image is safe to handle and it will not degrade. The print is dried in a clean environment and then it is ready for viewing, mounting, sale, or any other intended use.
In black and white photography, a darkroom is often lit with red or orange light so that photographers can see as they work on prints. Color photography requires complete darkness, as the developing paper must be sensitized to all wavelengths for the print to come out properly. It also requires more sophisticated enlargers with options like color correction.