Patent GB-883334-A (GB)
Title: Improvements in or relating to photographic cameras equipped for adjustment by exposure values
IPC: G03B7/00
Filed: 1958-01-28
Abstract: 883,334. Photographic cameras. DECKEL, H., and DECKEL, F. W. Jan. 28, 1958 [Jan. 29, 1957; Dec. 9, 1957], No. 2802/58. Class 98(1). In a camera having an interchangeable lens and an exposure meter in the camera body, coupling elements of a drive between an exposure meter follower and the shutter and diaphragm are disconnected and are locked in the position in which they are disconnected by detachment of the lens mount. As shown, pinion 52 drives the cage 40 of a differential as in Specification 878,153. Shaft 54 is driven by shaft 218 and telescopes therein to permit focusing the lens. On rotating the lens mount to free the arm 234 and disconnect the bayonet joint attaching the mount to the camera, arms 240 and 236 enter previously positioned notches 244 and 238 in shafts 242 and 218 and, as in Specification 770,821, the coupling siots in shutter setting shaft 242 and shaft 218 are normal to their respective axial planes to permit disengagement of the coupling. Shaft 242 on the camera body may either be locked by a pawl member engaging a notch therein or, alternatively, by a friction brake. In another form, Figs. 5, 6 and 7, bayonet lugs 308/312 are carried on ring 306 in screwthreaded connection with member 304. Plunger 390, 396 extends into notch 310 of ring 306 to prevent it from being rotated when the mount is removed from the camera. On replacing the mount, the return of the plunger simultaneously unlocks coupling element 360 and frees knob 338 by disengagement of tooth 386 from notch 348 in disc 346. Thereafter rotation of knob 338 turns cam 330 to adjust follower 326 into coincidence with pointer 324 of exposure meter 322. When knob 338 is turned into the position in which it is locked, cam groove 342 frees ring 306 from latch 376 to permit removal of the mount. Coupling element 362 (Fig. 7) is locked on withdrawal of the mount by plunger 402 engaging notch 400 in disc 398. Figs. 13, 14 (not shown) illustrate a double bayonet joint and a modified locking arrangement using only a single member for both ring 306 and shaft 358. In Fig. 15 removal of the lens mount locks only the coupling element 360<SP>1</SP> and leaves the knob 338<SP>1</SP> free to turn. Ring 306<SP>1</SP> drives shaft 358<SP>1</SP> through internally toothed gear segment 432 and gear 434 having pin 436 coacting with arm 438. The locking of ring 306<SP>1</SP> in the lens free position holds shaft 358<SP>1</SP> at the end of its travel and torsion spring 442 tensioned. Arm 440 is held clear of pin 448 on bevel gear 446 which thus rotates freely on shaft 358<SP>1</SP> as knob 338<SP>1</SP> is turned. When, on reconnecting the bayonet joint, pin 436 is rotated away from arm 438, spring 442 drives arm 440 until it abuts pin 448 whatever the position of the latter may be. It is further suggested, additionally or alternatively, that a resilient lost-motion connection acting in the same way as 436, 438, 442, 440 and 448 may be provided in shaft 364<SP>1</SP> so that the diaphragm aperture and shutter speed may be freely adjusted while the coupling element 362<SP>1</SP> is locked. A fixed lens camera having a detachable diaphragm is referred to. If the exposure meter has more than one range of measurement, a follower may be provided for each range.