GB864867A - Mechanism for adjusting photographic cameras in terms of exposure values - Google Patents

Abstract

864,867. Photographic cameras. DECKEL, H., and DECKEL F., W. Jan. 20, 1958 [Jan. 25, 1957], No. 1838/58. Class 98(1) In a photographic camera, an exposure meter pointer follower 102a on an exposure value indicator is operated by an arm 76a rotatable about an axis parallel to the optical axis by means of a centrally pivoted member 68 co-operating with edge cams 64 and 66 on rings 54 and 58 rotatably mounted in a lens mount and coaxial with the optical axis. Compensating adjustments of the shutter speed and diaphragm aperture, which do not vary the amount of light received by the film, rotate cams 64 and 66, respectively, so that member 68 turns about the pivotal axis 74 while the position of arm 76a remains unchanged. Cams 64, 66 may be stamped from pre-hardened material and more than one cam may be provided on each ring 54, 58. An additional cam may, for example, be used to allow for film sensitivity. As shown in Fig. 2, an exposure value scale 90 is viewed through a window in the lens mount and the scale ring 88 is driven by arm 76 through pinion 84. The shutter and diaphragm are constructed so that equiangular displacement of their adjusting rings 28 and 34, respectively, bring about compensating adjustments of shutter and diaphragm. To adjust the exposure value scale the rings 28 and 34 are moved separately and a catch holding ring 28 stationary is less easily over ridden than the engagement of spring catch 48 with notches 52 in ring 34 so that ring 34 may be turned alone without holding ring 28 stationary. Catch 48 may alternatively be omitted or replaced by a coupling which is only operative to lock rings 34 and 28 together when the latter is turned. In another form (Figs. 7 and 8, not shown) the scale carrying part of the diaphragm adjusting ring 34 is displaceable relatively to the remainder of the ring in accordance with the speed of the film and engaged therewith by means of a spring-pressed ball-catch. The lens mount may be interchangeable. Specification 798,038 and Austrian Specification 200,910 are referred to.