Motion picture camera with fade-in and fade-out effects during long-term exposure
AssigneesKarl Vockenhuber, Raimund Hauser
InventorGerd Kittag
Life of this patent
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Abstract
A motion-picture camera switchable to long-term exposure, in the presence of insufficient illumination for normal filming, has a photodetector which in the long-term mode controls a timing circuit measuring the length of an exposure period during which the camera shutter is arrested in an unblocking position, that period varying inversely with the detected intensity of incident light. In order to provide a fade-out effect at the end of a scene taken in this manner, the exposure period is progressively shortened--or the diaphragm aperture is progressively reduced--in discrete steps during successive shutter cycles to substantially complete cutoff. For fade-in at the beginning of a scene filmed with long-term exposure, the opposite procedure is followed.
Claims14
In a motion-picture camera provided with a picture-taking objective for illuminating successive frames of a film moving past an image gate in line with said objective, a shutter movable into and out of a blocking position obstructing said image gate, drive means for intermittently transporting the film past said image gate while moving said shutter into its blocking position during advances of the film from one frame to the next, timing means operable to arrest said drive means in an unblocking position of said shutter for a variable exposure period forming part of a shutter cycle, and photometric means operable to control said timing means for varying the duration of said exposure period generally inversely with the intensity of illumination traversing said image gate, said timing means including a storage capacitor and a threshold circuit connected across said storage capacitor for integrating an electrical output variable of said photometric means to emit a pulse terminating said exposure period upon attainment of a capacitor charge corresponding to a reference level established by said threshold circuit,
- the combination therewith of fading-control means adapted to be operatively coupled with said timing means for changing the exposure of successive frames between a predetermined maximum value and a predetermined minimum value, said fading-control means comprising a signal generator connectable to said threshold circuit for progressively modifying said reference level to alter said exposure period by discrete increments during successive shutter cycles.
In a motion-picture camera provided with a picture-taking objective for illuminating successive frames of a film moving past an image gate in line with said objective, a shutter movable into and out of a blocking position obstructing said image gate, electrical drive means for intermittently transporting the film past said image gate while moving said shutter into its blocking position during advances of the film from one frame to the next, photometric means measuring ambient illumination, switchover means having a first position for the establishment of a normal operating circuit for said drive means with continuous movement of said shutter and having a second position for the establishment of a long-term operating circuit for said drive means, said long-term operating circuit including timing means controlled by said photometric means for the emission of a series of pulses at a cadence varying with the intensity of illumination traversing said image gate, said drive means being responsive to said pulses in said second position of said switchover means for arresting said shutter in an unblocking position for an exposure period which forms part of a shutter cycle and varies in duration generally inversely with said intensity of illumination, and trigger means for operating said drive means,
- the combination therewith of fading-control means selectively activable in said second position of said switchover means for changing the exposure of successive frames between a predetermined maximum value and a predetermined minimum value, said fading-control means comprising a signal generator actuatable in response to the emission of said pulses by said timing means to produce a stepped control signal for progressively modifying an exposure-determining parameter by discrete increments during a predetermined number of successive shutter cycles.
In a motion-picture camera provided with a picture-taking objective for illuminating successive frames of a film moving past an image gate in line with said objective, a shutter movable into and out of a blocking position obstructing said image gate, drive means for intermittently transporting the film past said image gate while moving said shutter into its blocking position during advances of the film from one frame to the next, timing means operable to arrest said drive means in an unblocking position of said shutter for a variable exposure period forming part of a shutter cycle, and photometric means operable to control said timing means for varying the duration of said exposure period generally inversely with the intensity of illumination traversing said image gate, said timing means including a storage capacitor and a threshold circuit connected across said storage capacitor for integrating an electrical output variable of said photometric means to terminate said exposure period upon attainment of a capacitor charge corresponding to a reference level established by said threshold circuit,
- the combination therewith of fading-control means adapted to be operatively coupled with said timing means for changing the exposure of successive frames between a predetermined maximum value and a predetermined minimum value, said fading-control means comprising a signal generator connected to said storage capacitor for progressively modifying the charge thereof independently of said photometric means by discrete increments during successive shutter cycles.
Dependencies are inferred from the claim text.