GB701041A - Optical viewing apparatus - Google Patents

Abstract

701,041. Optical viewing apparatus: photographic cameras. VOIGTLANDER & SOHN AKT.-GES Aug. 25, 1950 [Sept. 28, 1949] No. 21090/50. Classes 97(1) and 98(1) In optical viewing apparatus having a substantially opaque screen in the light path between an object and one eye of an observer, said screen incorporating a substantially transparent mask and a small transparent area or 'aperture having a single boundary, and an optical system so that said one eye of the observer sees an image of the mark superposed on the wide object field seen by the other eye and at the same time sees through the small area or aperture a restricted view of the object and receives therethrough one beam of a range-finder, the optical system consists of or includes an annular element or elements so that the beam passing through the small area or aperture is not reflected or refracted by the optical system. As shown in Fig. 4, the view-finder comprises an opaque screen having a transparent mark N and a central aperture D and lying in the light path between an object and the right eye R of an observer whose left eye views the whole object field. Through aperture D passes one beam of a range-finder which is combined at H with the other beam reflected at U and the combined beams pass to the eye through an aperture O in a lens K which also serves to form an image of the mark that appears to be superposed on the object. Lens K may be replaced by a pancratic optical system and a telescope, which may be pancratic, may be positioned in the light path between the object and the other eye. The apparatus maybe mounted on a photographic camera, Fig. 5, so that either eye Q can look through it. To eliminate parallax, the annular lens K is mounted on an arm C pivoted at E and movable over a scale G. The image of the mark may indicate the boundary of the image of the object formed on the film in the camera by an objective of certain focal length and in order that different camera objectives may be used each objective is mounted as a unit with the screen having the mark corresponding thereto. In Fig. 9, five camera objectives are mounted on a turret T and the arrangement is such that one eye L views the object through the lens (e.g. N4) which is adjacent to the photographing lens (e.g. N3) which the other eye R sees a restricted view of the object through the central aperture of screen M and also an image of the mark on the screen superposed on the object. The ratio between the focal lengths of neighbouring objectives is approximately constant so that the size of the image of the mark formed by lens K will be substantially correct for all the objectives. Screen N may be replaced by two relatively adjustable screens M<SP>11</SP> and M<SP>12</SP>, Fig. 10, whereby the size of the central area M<SP>13</SP> can be adjusted, for example, by the focusing mechanism of the camera. Specifications 454,064 and 639,409 are referred to.