Sharpness-determining device

摘要

A sharpness-determining device is disclosed in which an object image generated on a prescribed focal plane of a photolens is once again projected by a second projecting optical system behind this focal plane into two object images which are not located one above another and are based on light bundle sections which are split up symmetrically relative to the optical axis of the photolens; light-sensitive elements are respectively arranged at the points at which these object images are once again projected by the second optical system; a sharpness state of the photolens is determined by using these light-sensitive elements to detect the relative spatial relationship of these object images projected once again. The sharpness-determining device comprises a beam-splitting device which is arranged in the second optical system and splits up a light bundle, coming from the exit pupil of the photolens, into a central section and an edge section. Using this arrangement, it is possible by means of the second optical system to obtain an object image which is required in accordance with the varying f-number of the exit pupil of the photolens, or an object image which simultaneously allows the use of a further determining process with this device.