Wide-angle variable lens system for reflex cameras comprizes first negative and second and third positive lens groups with diaphragm between using specified group intervals for focal length settings.

摘要

The wide-angle variable lens system includes a negative lens group (10), a diaphragm (S) and a second positive lens group (30) arranged in this sequence viewed from the subject side. The lens groups are so moved on change of focus from shortest to longest focal length that the interval between first and second lens groups diminishes as also between second and third lens groups (20,30). This satisfies the condition (D2S-D2L)/(fL-fS) to be maximum 0.7. In this, (D2S) denotes the interval between second (20) and third (3) lens groups when set to shortest focal length and (D2L) when set to longest focal length. (fL) denotes the system focal length at longest setting and (fS) that at shortest setting. In a second condition, (f23S/f2) is between 0.25 and 0.5 and in this (f23S) is the summated focal lengths of second and third lens groups at shortest setting, and (f2) is the focal length of the second group (20). The diaphragm (S) moves together with the third lens group (30).