Optics: motion pictures – Camera and/or projector drive mechanisms
Reexamination Certificate
2001-05-09
2003-02-25
Adams, Russell (Department: 2851)
Optics: motion pictures
Camera and/or projector drive mechanisms
C352S067000
Reexamination Certificate
active
06523956
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to film, video, and electronic imaging technology and, more particularly, to an apparatus and method for special effects moving image photography.
BACKGROUND OF THE INVENTION
In photography and image processing every method and piece of equipment has both advantages and limitations when it comes to manipulating the visual qualities of images. Inventors have attempted to overcome limitations on, and add functionality to, certain prior art camera devices by devising systems which produce, and in some cases record, multiple optical images.
One group of such prior art consists of camera devices designed to use black and white film to reproduce color images. In these devices each of the multiple image paths is filtered to transmit a different portion of the color information. An example of such a camera device is shown in U.S. Pat. No. 2,027,369 to Bourges, which discloses multiple motion picture cameras, each fitted with an objective lens, which are mounted together in a unit, and combined with multiple beam splitter mirrors positioned in front of their objective lenses such that the resulting angle of view of the cameras is identical.
The use of beam splitter mirrors in front of multiple objective lenses creates significant optical limitations. A two camera arrangement which uses a single such mirror will limit how wide-angle the objective lenses can be without “vignetting” the image. In a system with three or more cameras such as the Bourges device, (and with the resulting need for multiple beam splitter mirrors) the problem would be acute. It is also practically impossible to use zoom lenses in such a system, because of the difficulty of matching their focal lengths.
Camera devices that create multiple optical images of other configurations are also known in the art. One such group of prior art consists of so called “three chip” video cameras, which utilize three electronic image sensors to produce color images. An example of one of these devices is U.S. Pat. No. 4,275,412 to Contant, which discloses a beam splitter prism positioned behind a single, shared objective lens, with the prism used to divide the image produced by the objective lens and direct a copy of that image to each of three electronic imaging sensors. Placing the beam splitter behind the objective overcomes the above-described limitations, and prisms are conventional to be optically superior to mirror or pellicle beam splitters for this purpose. These prior art devices create multiple optical images, but the individual sensors are incapable of producing images that contain complete picture information. A combination of the information from all of the sensors is necessary to reproduce the color of the original scene. The limitation is the same whether the cause is filters inserted in each optical path or the design of the imaging sensors.
This type of video camera is also limited by the fact that it is incapable of making separate recordings of the images produced by the multiple imaging sensors. Information from the three sensors is first combined electronically, and a single recording is made of the combined information. These camera devices are further restricted by the limited functionality of their electronic image combination means. The above limitations prevent such camera devices from realizing potential additional advantages of utilizing multiple, rather than single, image sensors or film strips.
Camera devices that utilize multiple image recording devices in combination with a beam splitter positioned behind an objective lens are also disclosed in the prior art. One example of such a device is a device designed to use black and white film to reproduce color images. This device discloses three film transport mechanisms associated with multiple image paths, each of which is filtered to transmit a different portion of the color information, and all of which are synchronized to make their separate exposures simultaneously. As part of the original “Technicolor” process, the filtered images were developed and combined in a motion picture film laboratory.
The synchronization of the multiple camera mechanisms is maintained to a very high degree of precision because, if they were not, the resulting images would be rendered unusable by color distortions. Precise adherence to the synchronization pattern is insured by fixed mechanical interconnections between the multiple camera mechanisms, and between those mechanisms and the camera's motor. The fact that it includes no provision for individually adjusting the “speed” (frames per second/f.p.s.), and the synchronization or relative timing of the three camera mechanisms prevents this camera device from realizing potential additional advantages.
Another example disclosed in the prior art is not as limited. This device is specifically designed to produce the effect of an instantaneous change from conventional to slow motion moving images. The effect is completed by editing or “cutting” from an image sequence recorded at one camera speed to an image sequence recorded at a different camera speed. In order to create the required image sequences this device allows two camera mechanisms with a matching point of view to operate at different speeds relative to each other. This device is limited by the fact that there is no incorporated or extent device compatible with this or other camera devices for coordinating or synchronizing in a precise manner the exposure cycles of cameras operating at different speeds and/or when the exposure cycles of those cameras are synchronized and offset relative to each other, and the cameras are operating at low speeds, i.e., below 15 f.p.s.
Certain other limitations on the above described prior art devices result from the fact that their film strips or image sensors are exposed directly to the image formed by an objective lens. In such an arrangement there is only a short distance between the rear of the objective lens and the focal planes of the multiple images. Consequently there is extremely limited space available for a beam splitter prism and the associated film gate structures or image sensor devices. These space restrictions prevent the use of larger camera mechanisms such as existing film or video cameras, and necessitate the use instead of specially constructed and permanently installed camera mechanisms or electronic image detectors.
One solution to these space restrictions calls for the use of optical relays. Optical relays, which extend the distance between the rear of an objective lens and the focal plane of the image sensor or film gate into which the final image is projected, are generally known in the prior art for use with a single camera device. An example of a motion picture camera optical relay is shown in U.S. Pat. No. 5,727,236 to Frazier, which discloses an arrangement of an objective lens, a field lens and a relay lens such that the image originally formed by the objective lens is transmitted by the other lenses to the film of a film camera or the electronic imaging detector of a video camera. The Frazier device and others also allow the focus of the final image to be adjusted by the relay lens instead of the objective lens. However, the prior art has failed to provide a multiple axis optical relay having a plurality of associated camera mechanisms.
The ability of prior art moving image camera devices, including those which produce multiple images, to control the extremely short “bursts” of electronic flash lighting is also restricted by limitations in conventional camera shutters. A conventional flash device currently in use in the motion picture industry emits light in bursts that have a duration of {fraction (1/100,000)}th of a second. In contrast, the conventional shutter in a typical professional film camera, limited by its relatively compact size, and operated at normal camera speed (i.e., 24 f.p.s.), can generate a maximum shutter “speed” (minimum exposure time) of only {fraction (1/200)}th of a second. A potential advantage of multiple image camera
Adams Russell
Esplin D. Ben
Ostrager Chong & Flaherty LLP
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