Photographic lenses have been manufactured for more than 100 years, and theoretical studies have also been continued throughout. Therefore, the progress was rather steady than striking. In recent years, however, some new types of the lenses have been developed, owing mainly to the use of new optical glasses and the introduction of an electronic computer to the lens design. Attempts have also been made to design lenses favorable for given camera mechanisms or properly corrected for newly developed emulsions. These trends will be discussed from the lens designer's viewpoint.
