As with a camera, the lens of the enlarger is the heart and should be high quality and reasonably fast. It is senseless to buy high-quality lenses for the camera, then nullify the quality they provide with an inferior enlarging lens; however, a quality camera lens is not suitable for enlarging. Even a moderately good enlarging lens is better for enlarging than most camera lenses.

Table 11-1. Enlarging Lens Focal Lengths for Various Negative Sizes

The focal length you use with an enlarger should be based on the size of the negative to be enlarged. (See table 1l-1.) Generally speaking, the focal length of the enlarging lens for a given negative size should be the same as a normal-focal-length lens used by the camera for the negative.

While it is not necessary for the lens to cover the full area of the negative, the longer the lens focal length, the less magnification at a given lens-to-paper distance; therefore, you must have several lenses of various focal lengths available for your enlargers when you want to make large prints from small portions of your negatives.

Because an enlarger produces an image from a flat field (the negative) onto a flat field (the paper), depth of field is not a factor, except when distortion control (discussed later) is used. An enlarger lens can usually be used at large f/stops; however, when an enlarger lens is used at its maximum aperture, there may be some falloff of light at the edges of the circle of illumination. Therefore, an enlarger lens is usually stopped down one or two f/stops from wide open. Like a camera lens, when an enlarger lens is used at very small apertures, there is a loss of image definition due to diffraction.

ENLARGING PROCEDURE

The darkroom design, the equipment, and the arrangement for enlarging are basically the same as for contact printing. The safelights should be appropriate for the type of paper being printed. The size of the prints may require larger trays and greater amounts of solution, but they should be set up in the sink the same as for contact printing.

To produce good enlargements, you need good negatives, a clean enlarger, clean printing filters, correct exposure and development, and careful processing and finishing. Although most negatives can be printed by projection, there are a few desirable characteristics. A good negative has normal density and contrast. It must be sharp and free from such defects as scratches, abrasions, dust, lint, and fingerprints.