GB793178A - Improvements relating to devices for indicating depth of focus in photographic cameras - Google Patents

Abstract

793,178. Photographic cameras. DECKEL, H., and DECKEL, F. W. Dec. 28, 1955 [Jan. 5, 1955], No. 37118/55. Class 98(1) In a photographic camera, one depth-of focus pointer is driven through a link pivotally connected to a ring driven by the diaphragm control mechanism and having a control pin guided in a stationary curved guideway and the other pointer is driven from the first by gearing which' moves it equally in the opposite direction. Preferably, link 40 is carried on pivot pin 36 on diaphragm follower ring 30 and control pin 46 rides in slot 48 of stationary ring 50. Link 40 is connected to ring 16 by pin 42 engaging radial slot 44. Meshing pinions 22 and 24, mounted on fixed ring 20, mesh with rings 16 and 18 respectively so that pointer 12 can be moved equally and oppositely to pointer 10. In a lens mount (Fig. 2), having the front optical element movable axially, on rotating ring 90, for focusing, a range scale is carried on the periphery 92 of ring 90 and co-operates. with the pointers 10, 12 and a reference mark (not shown), on the external part of fixed ring 20. Space 64 is provided to accommodate the shutter mechanism and the shutter speeds are set by ring 72 carrying a shutter speed scale co-operating with this reference mark. A diaphragm operating ring 66 engages lug 32 driving ring 30 and is connected to a diaphragm setting ring 74. This ring is movable axially against spring pressure of ring 66 to free it from toothed engagement with ring 72 so that the diaphragm aperture can be adjusted without simultaneously adjusting the shutter speed. When rings 72 and 74 are rotated together the shutter speed and diaphragm aperture undergo compensating variations so that the light quarter remains constant. A light value scale on ring 74 and a reference mark on ring 72 may be provided instead of, or in addition to, a diaphragm aperture scale 34 on ring 74 which co-operates with the reference mark on fixed ring 20. A corrugated annular spring 98 holds the arrangement shown in Fig. 1 in place in the lens mount. Specification 744,962 is referred to.