Tilting viewfinder and video door accessory for motion-picture camera

An accessory video door and tilt viewfinder for use with an ocular and with a video camera, and with a motion-picture camera which throws onto a ground glass at the side of the motion-picture camera, very near the front thereof, an inverted image of a scene;

• said accessory comprising:
• a case adapted to be supported from such motion-picture camera adjacent to such ground glass, and to form a substantially light-tight seal with such motion-picture camera;
• said case in use accepting from such image, very near the front of such motion-picture camera, light rays that are generally at a right angle to such side of the motion-picture camera;
• a viewfinder tube having two ends, a first one of the ends being pivotally mounted to the case and forming a substantially light-tight seal with the case, said tube in use receiving from the case light rays originating from such image;
• an attachment port, defined at the second end of the tube, for mounting of such ocular;
• a reflector within the tube near the first end, for receiving light rays from the case, generally at a right angle to such side of the motion-picture camera, and for deflecting the received light along a pivoting optical path, within the tube, that is very generally parallel with such side of the motion-picture camera;
• a relay lens, substantially fixed within the tube, for receiving deflected light from the reflector and relaying such image to a point near such ocular for viewing, the lens also having the effect of inverting the image;
• the relayed image at said point being subject to rotation about the pivoting optical path, due to pivoting of the tube relative to the case;
• a Pechan prism, rotatably secured within the tube, for counterrotating the relayed image in compensation for said image rotation due to pivoting of the tube, the Pechan prism also having the effect of inverting the image;
• an Amici prism, disposed within the case, for redirecting light rays from the image on the ground glass along a fixed optical path within the case, rearward of such motion-picture camera and generally parallel to such side of the motion-picture camera, and for inverting the image to compensate for inversion by the Pechan prism;
• a video attachment port in the case, behind the Amici prism relative to such motion-picture camera, for attachment of such video camera to monitor such scene;
• and
• a beam splitter that passes part of the light from the Amici prism rearward of such motion-picture camera to the video attachment port, and that deflects part of the light from the Amici prism generally at a right angle to the fixed optical path, for passage to the reflector within the tube;
• whereby the Amici prism and beam splitter in combination facilitate reimaging of such scene at such video camera, and also effectively move such ground-glass image rearward of such motion-picture camera, away from the front thereof, for passage into the tube, so that the tube is clear of the front of such motion-picture camera;
• and
• whereby such cameras and ground-glass image, and the case, may be tilted vertically while such viewfinder tube and relayed image, and the ocular, may be held at a substantially unchanged position vertically with such relayed image maintained substantially erect.