GB710622A - Improvements in and relating to objectives - Google Patents

Abstract

710,622. Optical objectives. VOIGTLANDER AKT.-GES. Sept. 4, 1952 [Feb, 4, 1952], No. 22250/52. Class 97(1) In an objective in which a stop lies between two lens combinations each consisting of, from front to rear, a single uncemented meniscus lens followed by a compound doublet component of opposite sign, the rear combination consists of two simple meniscus dispersing lenses concave to the stop enclosing a simple collecting lens having unequally curved surfaces, the said last two lenses having an adjacent pair of surfaces concave to the stop and having a collective equivalent refractive power, the arithmetic mean of the refractive indices of the lenses of the rear combination is greater than 1.5750 while the collecting lens of the rear combination is so bent that the surface refracting power, referred to air as the bounding medium, of the more strongly curved outer surface of this lens which is concave to the stop and belongs to the said adjacent pair of surfaces is between 1.5 and 4.5 times the equivalent refractive power of the whole objective. Numerical data are given for one example of the objective shown.