Patent ID: 7276686

Claim:
A method for detecting a shutter opening angle of an adjustable rotating shutter mounted in a film camera which comprises a circular segment or circular sector shaped shutter vane driven through a shutter shaft by a shutter motor, and a shutter adjustment vane mounted coaxial with the shutter vane and adjustable relative thereto by means of a shutter adjustment vane motor, the method comprising: detecting an absolute position of the shutter vane and an absolute position of the shutter adjustment vane with a resolution of n steps during one revolution of the rotatable shutter, and determining the shutter opening angle (α) a of the rotatable shutter ( 1 ) from the equation α=[ P BF −P VF] *360 °/n wherein P BF is the position of the shutter vane and P VF is the position of the shutter adjustment vane, wherein when the value of angle α is less than 0° the value is increased by 360° as long as the resulting value is greater than or equal to 0° or when the value of angle α is greater than or equal to 360° the value is reduced by 360° as long as the resulting value is less than 360°.