Improvements in six-element lens

884,156. Optical objectives. ZEISS JENA, CARL VEB. April 24, 1959, No. 14126/59. Class 97(1). A six element objective comprises two convergent menisci followed by a dispersing meniscus, a biconcave element and two convergent elements, the focal length of each of the convergent menisci differs from the focal length F of the objective by not more than Π5%, the absolute focal length of the dispersing meniscus and that of the biconcave 9 1 element are each between - F and - F and 20 2 the focal length of each of the two convergent 3 17 elements is between - F and - F. Preferably 4 20 the glasses used in the objective lie in the V d :n d diagram below the straight line n d + 0.00744 V d = 2-1. Optical data are given for one example of the objective shown.