Exposure control system for flash photography
AssigneeCanon Kabushiki Kaisha
InventorsShohei Ohtaki, Zenzo Nakamura, Susumu Kozuki
Life of this patent
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Abstract
A flash exposure control system comprising a flash lighting unit, a battery circuit connected to said flash lighting unit to energize said flash lighting unit during an exposure, a switching arrangement connected to said flash lighting unit to control the termination of energization of said flash lighting unit, a timer for controlling the conduction of said switching arrangement, the timer having an adjustable circuit for adjusting the duration of conducting time as a function of the camera-to-object distance and the adjustable circuit being responsive to the camera focus adjustment, and an aperture adjusting unit responsive to the focus adjustment for defining an exposure aperture.
Claims10
A flash exposure control system for use with a photographic camera comprising:
- flash lighting means;
- circuit means connected electrically to said flash lighting means to energize said flash lighting means;
- angle changing means engageable with said flash lighting means to change the flash angle of said flash lighting means on the basis of distance to an object, said changing means being operative for changing the flash angle of said flash lighting means over a first set of angles corresponding to distances from the object greater than a given distance, said changing means being operative for changing the flash angle of said flash lighting means over a second set of angles corresponding to distances less than the given distance;
- light energy control means coupled to said flash lighting means and coupleable with said angle changing means for controlling the light energy level of the flash lighting means in a first range when the flash angle varies within the first set of angles, said light energy controlling means being operative for controlling the level of the light energy in a second range when the flash angle varies within the second set of angles, the light energy level in the first range being dependent upon the flash angle, the light energy level in the second range being less dependent on the flash angle than in the first range.
A flash device for use with a camera having an objective with a distance adjusting component as well as a diaphragm regulating mechanism having impedance means coupled with the distance adjusting component:
- comprising a flash unit including support means for rigidly securing the unit to the camera and illuminating means rotatably mounted on said support means, said illuminating means including angular position setting means for varying the direction of illumination with respect to the optical axis of the objective, control circuit means connected to said illuminating means and mounted on said support means, said control circuit means including a timing circuit for controlling the time of energization of said illuminating means and having an impedance means for varying the energization time, said impedance means of said timing circuit when said flash unit is secured to the camera being coupled to the distance adjusting component to vary the energization time, a flash lighting source electrically connected to said flash unit and having a power source and a control circuit connected to the output of said power source, said control circuit including a switching circuit connected between said illuminating means and said power source and a control signal forming circuit, said control signal forming circuit being connected to said impedance means of said timing circuit and to said switching circuit to apply a light control signal to said switching circuit corresponding to the selected distance.
A flask device for use with a camera having an objective with a distance adjusting component as well as a diaphragm regulating mechanism having impedance means coupled with the distance adjusting component:
- comprising a flash unit including support means for rigidly securing the unit to the camera and illuminating means rotatably mounted on said support, means, said illuminating means including angular position setting means for varying the direction of illumination with respect to the optical axis of the objective, control circuit means connected to said illuminating means and mounted on said support means, said control circuit means including a timing circuit for controlling the time of energization of said illuminating means and having an impedance means for varying the energization time, said impedance means of said timing circuit when said flash unit is secured to the camera being coupled to the distance adjusting component to vary the energization time, a flash lighting source electrically connected to said flash unit and having a power source and a control circuit including a switching circuit connected between said illuminating means and said power source and a control signal forming circuit, said control signal forming circuit being connected to said impedance means of said timing circuit and to said switching circuit to apply a light control signal to said switching circuit corresponding to the selected distance said control circuit comprising;
- adjusting means associated with the illuminating means and operatively connected to the impedance means so as to adjust the timing circuit to the shortest timing operation when the illuminating means is rotated.
Dependencies are inferred from the claim text.