CAMERA

摘要

1513215 Exposure control FRANKE & HEIDECKE GmbH [trading as ROLLEI-WERKE FRANKE & HEIDECKE] 10 June 1976 [6 Sept 1975] 24029/76 Heading G2E The light-sensitive element of an exposure control device in a motion picture camera receives light passing through the objective lens by reflection from the shutter and then from another reflecting surface, the second reflective surface being capable of occupying one of two positions according to whether the shutter is rotating or stationary, so that the light falling on the light-sensitive element is generally constant. As shown, light entering lens 1 passes through to the camera aperture 2, being intermittently interrupted by the conical surface 6 of a shutter 4 rotating on a shaft 3. The surface 6 reflects the light beam up to a further mirror 7 which reflects it again to the light-sensitive element 8 which is connected to an exposure metering or control device 9. Thus the beam of light reaching element 8 is also intermittent because of the rotating shutter 4. Mirror 7 is arranged in the centre of a roller 10 connected to a bracket 12, and pivotally mounted on a shaft 11. Bracket 12 is pivoted in opposite senses by springs 14, 15, until either arm 12a or 12b abuts against a stop 13. Spring 15, which is stronger than spring 14, is attached to an over-centre switch 16 actuated by a shutter release 17. When this is no longer pressed, the camera becomes inoperative, with the shutter stationary in the position in which it blocks the light from aperture 2. Since light is now permanently, and not intermittently, reflected from the shutter, the amount of light reaching element 8 would be considerably greater than while the shutter is rotating. To overcome this, the switch 16 changes over as release 17 is set free, so that the force of spring 15 is reduced sufficiently for spring 14 to become operative. Bracket 12 is now drawn clockwise from the position shown in the Figure until arm 12b abuts against stop 13. Mirror 7 thus assumes a different angle, so that not all the light falling on it is reflected to element 8. The amount of such light can be varied by bending the flexible arm 12b.