GB378429A - Exposure meter - Google Patents

Abstract

378,429. Photographic exposure meters. DREM PRODUCTS CORPORATION, 152, West 42nd Street, New York, U.S.A. May 9, 1931, No. 13801. Convention date, Sept. 24, 1930. [Classes 97 (i) and 98 (i).] An exposure meter of the extinction type comprises a casing having a lens system through which the object to be photographed is sighted, a light-regulating member, and a movable comparison member which is adapted to lie across the axis of the lens system during measurement but is moved away from the axis during sighting. As shown, the casing carries an object lens 5a, Fig. 5, and an eyepiece 3 fitted with a lens 5 and telescopically mounted in a sleeve 2 furnished with a bayonet slot 7 engaged by a pin 6. A slide 8, Figs. 4 and 7, carrying a comparison member C is normally pressed upwardly by a spring B to bring the member C into the axis of the lens system ; but may be depressed by an external knob 18 to provide a clear field for sighting. The light - regulating member comprises a revoluble plate 19 carrying a slotted frame 20 furnished with a stepped wedge or wedge slot and is rotated by a stud S, Fig. 9, engaging teeth 23. A shaft 24, Fig. 7, carrying the stud S, is fitted with an external head. The plate 19 is connected by a screw 26 to an external head 27 fitted with an arm 28 whereby the member 19 may be quickly returned to initial position. A scale plate carried by the head 27 co-operates with a fixed scale ring. In use, the eyepiece 3 is turned until the pin 6 engages the straight portion of the slot 7 and the device is sighted upon the object, the slide 8 being depressed by the knob 18 ; the slide is then released and the plate 19 is slowly turned by the stud S until the comparison field C becomes invisible.