GB876539A - Photographic diaphragm setting mechanism - Google Patents

Abstract

876,539. Photographic diaphragms with setting means for flashlight exposures. GAUTHIER G.m.b.H., ALFRED. Sept. 4, 1957 [Sept. 4, 1956], No. 27950/57. Class 98(1) The aperture of a photographic diaphragm is adjusted for flashlight exposures by means influenced by the settings of relatively adjustable scales of subject distance, type of flash and film speed and connected either to the subject distance or the type of flash scale. As shown the diaphragm is disposed in the objective shutter mount which supports an adjustable shutter speed ring 3, a rotatable ring 14 bearing a type of flash scale 8 and a window 14b through which a film speed scale 10 on a separate ring 16 is visible, a rotatable ring 13 carrying a resilient member 12 bearing an index 11 adjustable to set the flashlamp type used, and a subject distance scale 7 on a fixed ring 5. The shutter speed ring is set to a value appropriate for unsynchronized flash exposures, e.g. 1/30th sec.; the film speed is set in window 14b, the setting being maintained either by frictional engagement between the rings 14, 16 or by forming one of the knobs 15 on the ring 14 as a releasable pin engaging in holes in the ring 16; the resilient nose 12a is located in the appropriate notch 14a in the ring 14 to set the type of flash; and rings 14 and 16 are rotated together to set the index 11 on the subject distance scale 7 by a rearwardly extending pin 17 attached to the ring 16 and to a diaphragm adjusting member 2 altering the diaphragm and having an operating handle 2a. In an alternative embodiment employing a light value setting scale 22 instead of a shutter speed scale the light value scale is arranged to first reduce the shutter speed at maximum diaphragm aperture (settings 1 to 3) and then when the fastest speed is reached to reduce the diaphragm aperture for higher light values (settings 4 to 9), the diaphragm adjusting pin 17 being spring urged against a lug on the ring 3 carrying the scale 22. This scale bears symbols indicating the range in which adjustment of the diaphragm occurs, e.g. flashlamp bulbs, and may be differently coloured from the shutter speed adjusting portion and may have restraining means indicating the limits of diaphragm adjustment and either releasable or overcome by applying more force to the ring 3. Means are provided for synchronizing different kinds of flash lamps to the shutter speed used. In this arrangement the ring 16 is dispensed with and the ring 3 carries the film speed scale 10 and is in frictional or releasable engagement with the ring 14 and after setting of film speed and type of flash the subject distance setting is achieved by rotating the ring 3. The flash identification scale may comprise symbols of different shapes and colours instead of manufacturer's designations as shown or may consist of or comprise additionally a scale of flash factors.