1. Field of the Invention
This invention relates to varifocal lens systems of the conversion type having discretely changed focal lengths.
2. Description of the Prior Art
In the past, in the art of 35 m/m cameras in the past various means have been proposed for allowing for discrete change of the focal length of the lens system to perform while still maintaining the compact state of the lens system. In U.S. Pat. No. 3,388,650, the method of changing the magnification power proposed therein is by inserting a supplementary lens into the space between the master lens system and the image plane and by moving the master lens system entirely. Another proposal in Japanese Laid-Open Patent No. Sho 54-97423 is that a supplementary lens of 6-component lens form takes its place in the rear of the master lens system with change of the magnification power. These supplementary lenses are, however, large, and cannot be said to be suited for minimization of the bulk and size of the entire lens system.
Further, for distance of the use of the supplementary lens constituting part of a lens system having changed focal lengths, mention may be made of U.S. Pat. No. 4,318,592.