ABSTRACT
The early days of photography were characterized by the use of large-format cameras from whose negatives contact prints were made. Bigger images by projection printing or ‘enlargement’ were uncommon until the 1920s, when ‘miniature’ format usage increased and compact, efficient light sources became available. The basic requirements for an enlarging lens are those of a large aperture for focusing, no vignetting, even illumination across the field, and uniform performance across the image without favouring the axial region. Contemporary enlarging lenses designated ‘apochromatic’ have a reduced secondary spectrum and in addition to printing are used for microfilming, scanning and imaging on to charge coupled devices arrays. An enlarger lens must be designed to have minimal vignetting from mechanical reasons. Many enlarger lenses whose physical dimensions permit it have a 39 mm screw mount for attachment to the enlarger. A wide-angle enlarging lens for small and medium formats allows greater magnification for a given negative to easel distance.
