PHOTOGRAPHIC LENS OF REAR DIAPHRAGM TESSAR TYPE

摘要

PURPOSE:To attempt to make a compact type, and improve the correction of aberrations by using the 3-group 4-element lens system in which the axial length and interfacial space, etc. are specialized. CONSTITUTION:Positive meniscus lens, bi-concave lens, and positive cemented lens are so arranged on the optical axis that requirement formulas 1-12 may be satisfied where TL is axial length from the vertex of the first plane of lens, TD is axial length of the lens portion, Da is space interval between first-third planes, Db is space interval between fourth-seventh planes, D2 is lens thickness between first and second planes, D4 is space interval between fourth and fifth planes, R1, R4, R6 are radii of curvature of first, fourth and sixth planes in succession, N1-N4 are refractive indexes of media of positive meniscus lens, bi-concave lens, negative lens of cemented lens, and positive lens of cemented lens in succession, and V1, V2 are Abbe's number of media of positive meniscus lens and bi-concave lens in succession.