Patent GB-854653-A (GB)
Title: Single lens reflex camera
IPC: G03B19/12
Filed: 1959-04-01
Abstract: 854,653. Single lens reflex cameras. AGFA A. G. April 1, 1959 [April 16, 1958], No. 11117/59. Class 98(1) A single lens reflex camera with a pre-setting diaphragm includes a diaphragm adjustment device comprising a diaphragm aperture varying means and a setting member connected thereto by way of a friction coupling and operated by a driving device, and further includes an adjustable stop for the aperture varying means controlled by a diaphragm pre-setting device. As shown (Fig. 2) the diaphragm presetting device comprises an annular pre-setting ring 10, which is rotatable for setting the desired diaphragm aperture valve on scale 10b against a fixed index 1d on ring 1, a stop ring 11 rigid with ring 10, and an intermediate ring 12. On depression of the shutter release, ring 16 is made to rotate by the running down of a driving device housed in the camera body, and this rotation is transmitted by way of extension 16a of ring 16 to the toothed portion 3a with which it engages, in the setting member 3. Diaphragm aperture varying means 2 is likewise rotated, due to the friction between members 2 and 3, which members are urged together by wavy spring 6, until stop 2c, extending through recess 'c, engages stop 11a of the diaphragm pre-setting device, whereupon varying means 2 remains stationary having set the diaphragm mounted in ring 8 to the pre-selected aperture by way of control flange 2b, whereas member 3 continues its rotary movement to completion. In the return movement of ring 16, members 2 and 3 are again returned to the position of largest aperture of the diaphragm. Toothed portions 10d and 12 of the diaphragm pre-setting device are engaged by spring 4 rigidly attached to rotatable shutter speed setting member 14 for adjustment of the diaphragm and shutter in terms of light values. If only the diaphragm is to oe adjusted, member 10 is displaced forwardly against spring 13 until spring 4 no longer engages teeth 10d. Members 10, 11, 12 and 14 are kept in position by engagement of bayonet ring 1 with retaining lugs 15a on ring 15 which is screwed to the camera. An interchangeable objective may be provided with similar bayonet connection and diaphragm adjustment device. A distance scale 9a on rotatable setting member 9 co-operates with index 8a and depth of focus scale 8b on non-rotatable ring 8 fixed to ring 1. The shutter (not shown) may be of the roller blind type or of the pivoted blade type. Fig. 3 is a cross-section of the front of the camera body and shows the driving device in its idle position. On dupression of shutter release 28, control lever 26 and lever 21 which is connected thereto by latch 30, are pivoted downwards about pin 19, due to engagement of flange 26a by the release. Flange 21a on lever 21 pivots upwards, tensions one end of driving spring 20 and at the end of its movement operates lever 41 to release arm 22. Since the available power of spring 20, acting against pin 18a, is considerably greater than that of return spring 23, lever 18 pivots about pin 19, thereby moving pin 17 for rotation of ring 16 and actuation of the diaphragm setting device described above, and also pivoting reflex mirror 25 out of the path of the exposure beam (by coupling means shown in Fig. 1). At the end of the pivotal movement of levers 26 and 21, flange 30b on the latch 30 is engaged by detent 35. Towards the end of the rotary movement of operating ring 16, a stop 16b strikes against projection 32a of shutter latch 32, thereby releasing shutter holding member 34, which rotates in the direction indicated. Flange 34a comes against lever 36 and detent 35, and pivots latch 30 so as to release first lever 21 and then lever 26. On return of lever 21, tension in spring 20 is removed and spring 23 returns lever 18 and coupled ring 16 to the position shown in Fig. 3, thereby also returning the diaphragm mechanism and mirror 25 to their original positions. In an alternative embodiment, lever 21 is directly coupled to release 28.