Patent GB-512726-A (GB)
Title: Improvements in cameras for colour photography or cinematography
IPC: G02B27/14
Filed: 1938-03-14
Abstract: 512,726. Cameras for colour photography and kinematography; optical systems. RONCAROLO, E. March' 14, 1938. No. 7843. Convention date, July 22, 1937. [Classes 97 (i) and 98 (ii)] A camera for colour photography and kinematography provided with a beam-dividing prismatic block having at least one partially reflecting and partially transparent surface for producing a plurality of component images in different planes is characterised in that the block, together with separate objectives for focusing the component images and separate 'synchronously-driven rotary shutters, is mounted in a rigid casing immediately behind the beam entrance aperture, while sensitized layers or films on which the component images are focused are held by carriers mounted over corresponding apertures in. the casing. In a simple camera containing a block 2, Fig. 1, formed of two prisms, objectives 10, 10<1>, one at least of which is adjustable vertically and horizontally, and rotary shutters 6, 6', the beam components are intercepted by red and green light-filters, 7, 7<1>, respectively disposed in alignment with the panchromatic negative films, 9, 9<1> supported by teeth 13 on the casing. The camera is also suitable for three-colour still and motion pictures in which one only, e.g., the green, image is obtained by colour selection, the others, e.g., the red and violet, images being obtained by the application of an orthochromatic emulsion to the panchromatic film or layer 9. Figs. 2, 3 show a modified camera in which the beam-dividing block 2<11 >is formed of four prisms, the internal surfaces of the upper and the side prisms being coated with transparent mirror plating to form two partially reflecting and partially transparent surfaces at rightangles to each other. The shutters 6, 6', 6" are driven in synchronism through bevel-gearing 12", and the filters 7, 7', 711 may correspond to the colours red, violet and green. The objectives 10, 10<1>, 10<11>, although, having the same characteristics, need not be identical, it being sufficient for two of them to be identical. By providing the objective diaphragm with different apertures it is possible to balance the three components of the beam. In the camera shown in Fig. 5, the block is formed of two prisms, the reflected beam being sub-divided by a similar smaller block 2', while the transmitted beam passes through a block 5 of plain glass. Fig. 6 shows a camera for taking fourcolour pictures with complete chromatic selection, and provided with a fifth objective having an inversion lens 17 which functions as a finder and a focusing objective. A frosted glass screen is placed in front of the lens 17. In a modification of the latter form of camera the left-hand block of prisms is placed at the back of the main block, and the fifth objective is omitted so that the main beam is only divided into four components. In this case objectives of short focal length and wide angle of aperture may be employed without the necessity for excessively large prisms. Fig. 8 shows a camera for taking three-colour pictures having a beam-divider formed with four prisms and provided with reflecting prisms 4, 4'. A modified three-colour camera comprises three dividing blocks 2, 2', 4, Fig. 9, the partially reflecting and partially transparent surfaces of which are disposed so as to allow a greater quantity of light to be directed to those component images having less actinic colour.