Patent GB-865526-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B7/06
Filed: 1957-07-22
Abstract: 865,526. Photographic cameras. GAUTHIER G.m.b.H., A. July 22, 1957 [July 24, 1956], No. 23148/57. Class 98(1) [Also in Group XXV] In a photographic camera having an interchangeable lens mount fitted with a built-in diaphragm, and also having a coupled exposure meter, the diaphragm blades are arranged on two rings mounted for relative rotation coaxially with the lens, the first ring being coupled (when the lens is fitted to the camera) with a shutter speed adjusting ring on the camera body, and the second ring being connected to a control member on the lens mount which is coupled to a follow up member of the exposure meter. As shown in Fig. 1, a camera has a body 1 with a detachable objective mount 2. A ring 3, mounted on the body 1 coaxially with the objective mount, is connected to the shutter speed setting mechanism and carries an index mark 4 co-operating with a fixed shutter speed scale 5. An exposure meter 6, mounted in the camera body 1, has a pointer 7 visible through a window 15 and a disc 9 on which a ring 10 is adjustable to allow for the effect of film speed. An index 11 on ring 10 is brought into correspondence with the pointer by means of channelled scale 16. This adjustment is effected as follows: a pinion 17 connected to disc 9 meshes with a gear-wheel 18, which bears a pin 21 spring-urged against a slidable pin 23. The other end of the pin bears on one arm of a bell-crank lever 25, the other arm of which bears on a pin 26, which, at its other end, engages a cam surface 31 (see also Fig. 2) formed on a ring 32 rotatably mounted on lens mount 2. The lens mount houses an iris diaphragm, the blades 27 of which are connected at opposite ends to rings 28, 29. Ring 28 is coupled to ring 3 by an arm 28a engaging a ring 30, and an arm 30a of ring 30 engaging ring 3. Ring 29 is connected by an arm 29a to the ring 32. Ring 30 bears an index 33 against which are read a shutter speed scale 34 marked on a fixed part of the lens mount, and a diaphragm scale 35 marked on a rotatable ring 53 connected to ring 29. In use, by rotating ring 53, ring 29 is rotated together with ring 32 bearing cam 31, until the index 11 of the exposure meter is in correspondence with the pointer 7. Thereafter the shutter speed may be selected by rotating ring 3 which is connected to ring 28 via ring 30 for compensating adjustment of the diaphragm, the index 33 rotating with ring 30 to indicate the chosen combination of shutter speed and diaphragm aperture. In a modification, the slidable shaft 26 may be replaced by a rotatable shaft connected to the cam 31 and to the follow-up member of the exposure meter by levers, cams or gear-wheels. The scale 5 indicates the shutter speed set when the lens mount has been detached. Attachment means for lens mount. When the lens mount 2 is attached to the camera body 1 by means not requiring rotation of the mount (e.g. a threaded clamping ring), a pin on the camera enters a bore in the lens mount to locate the mount in a position where the coupling means engage, the diaphragm aperture and shutter speed being set to some given values. Fig. 3 shows a bayonet socket ring 38 on the camera body, having slots 38a for receiving radial pins on the lens mount. The lens mount is inserted in the camera so that a pin 39 on the camera body enters a bore 40 in the mount (see also Fig. 4), whereupon a locking ring 36 on the mount is rotated until the pins 37 thereon enter the slots 38a. The finger 42a on a spring-loaded slide 42 on the socket 38 closes the slots 38a, preventing the lens mount from being attached or detached, except when moved back by a pin 43 when the shutter is set to its fastest or slowest speed. In this position, the coupling member between rings 3, 38 is correctly oriented. To ensure that the lens mount can only be attached or detached when the diaphragm is set to a given position, a slide 45 on the mount normally covers the bore 40, but is moved by a pin 30a when the diaphragm is set to the given position so that a hole 46 therein registers with the bore 40. In an alternative attaching means, Figs. 5, 6, an attachment ring 47 has lugs 47a engageable by lugs 2a on the lens mount. The mount is held against unintentional unlocking by a lever 48 mounted on ring 47 and operated by a projection (not shown) on the lens mount. In this construction, the rings 3, 38 are connected by a ring 49 (corresponding to the ring 30 in Fig. 1 and bearing the index 33), which is spring-urged towards the camera body. Ring 49 is connected to ring 28 by means similar to that described above with respect to ring 30. When the lens mount is attached, a pin 51 on ring 3 bears against and displaces ring 49, which is rotated until pin 51 snaps into a groove 49a formed in ring 49. When the pin 51 is not engaged in groove 49a, means of known kind either lock the shutter release or cause a warning indication in the viewfinder.