GB541774A - Improvements in or relating to means for adjusting exposure times and stop values for photographic or cinematographic cameras - Google Patents

Abstract

541,774. Photographic cameras with exposure meters. ZEISS IKON AKT.-GES. April 17, 1939, No. 11626. Convention date, April 16, 1938. [Class 98 (i)] Means for adjusting exposure times and stop values in photographic and kinematographic cameras comprise a photo-electric exposure with indicating means which is brought to a definite position by adjustment of an associated resistance, together with a differential gear which causes adjustment of either the exposure time or stop independently of the other to produce consequential adjustment of the resistance and also permits simultaneous adjustment of both exposure time and stop to ther equivalent combinations of values without alteration of the resistance, means being provided for indicating the pairs of adjusted values. In the form shown, the differential gear comprises a sun wheel 3 connected by gearing to the exposure-time adjusting ring 1, a planet wheel 10 geared to the stop adjusting ring 11, and a second sun wheel 4 connected with the sliding contact 6 of the resistance in the circuit of the exposure meter. A scale of stops 7 rotates with the sun wheel 4, and a disc 12 rotates with the sun wheel 3 and carries an index mark cooperating both with the scale 7 and with a fixed outer scale of shutter speeds 13. In use, the stop scale 7 is turned to adjust the resistance until the indicator of the exposure meter is deflected to a fixed mark 14, the stop being thereby simultaneously adjusted but the disc 12 remaining stationary. Should it be desired to use another equivalent combination of stop and exposure time to that then indicated on the scales 7, 13 by the index on the disc 12, this disc is rotated until the desired combination is shown, causing simultaneous adjustment of the stop and exposuretime adjusting rings, whilst the scale 7 and contact 6 remain stationary. The contact 6 is secured to a spindle carrying a disc 8 having an adjustable coupling 5 with the scale 7 secured to the sun wheel 4 in order to allow a preliminary adjustment for the sensitivity of the exposure material to be made, a window 9 in the disc 8 exhibiting the adjustment value. In the case of kinematograph cameras the disc 12 is coupled either to means for adjusting the picture frequency or with means for varying the opening of a sector shutter.