Ein Verfahren Zur Messung der Kontrast-Übertragungsfunktion Photographischer Objektive

Abstract

The contrast K of a self-luminous or incoherently illuminated object is defined by K = (J max - J min)/(J max + J min) where J is the intensity of illumination. When an optical system forms an image of the object, the contrast is reduced, due to diffraction, aberrations, and veiling-glare. The reduction of contrast is a function of the size of the object (or the spacial frequency), the relative aperture of the imaging system and its state of correction. An apparatus is described for measuring this contrast transmission function for miniature camera lenses. The objective to be tested projects on to a narrow slit the image of a rotating grating having varying frequencies, and K = 1. A photomultiplier gives an output proportional to the intensity of transmitted light and a cathode ray oscillograph synchronised with the rotation of the grating gives a stationary representation of the light distribution in the image. Results obtained with this apparatus from miniature camera lenses are given and discussed for ...