Modern Lens Design, 2nd Edition

Chapter 15Wide-Angle Lenses with Negative Outer Elements

This chapter presents several lenses (Figs. 15.1 to 15.5) that derive their ability to cover a wide angular field from a construction that incorporates negative meniscus elements as the outer members. A glance at the path of the principal ray in any of the lens drawings will indicate one purpose of this construction. The outer negative lenses take a wide angular field in object and/or image space and convert it to a much smaller angular field inside the lens, a smaller field that is within the ability of the inner elements to handle. In addition, the wide spacing between the positive center member and the negative outer members provides the spacing between positive and negative power used ...