Feature
Compact zoom lenses
Because early photographic zoom lenses replaced either fixed focal length lenses or afocal attachments placed in front of the objective lens, it is not surprising that they contained a fixed rear portion that resembled a conventional photographic objective •and was referred to as a "prime" lens. The front zooming portion was usually afocal and, while normally only two groups are necessary to zoom and maintain focus, the need for a separate focusing group dictated the use of a third front group. Thus, the four-group zoom lens conceived.
Log in or become a member to view the full text of this article.
This article may be available for purchase via the search at Optica Publishing Group.
Optica Members get the full text of Optics & Photonics News, plus a variety of other member benefits.