Patent GB-195663-A (GB)
Title: Improvements in optical apparatuses, as photographic cameras, for reproducing the objects with their natural colours
IPC: G02B27/12
Filed: 1921-10-07
Abstract: 195,663. Russo, G. Oct. 7, 1921. Colour photography and kinematography.-Relates to a camera for reproducing objects in natural colours, which may also be employed for exhibiting the reproductions either by direct vision or by projection, of the kind comprising an objective of wide aperture producing a primary image, behind which are arranged a number of co-planar secondary lenses provided with appropriate colour filters, which resolve the primary image into a set of component colour images which are received upon a common plate or film. According to the invention, (1) a converging lens is placed at or near the position of the primary image, (2) a separate condenser is used for each partial image when the apparatus is used for projection, (3) a plane or curved ground glass is placed at the position of the primary image when the apparatus is used for direct vision, (4) diverging lenses are placed in front of the partial images to correct for curvature of the image, (5) the camera may be stereoscopic or kinematographic. In the form shown in Fig. 6, the camera comprises an objective a adjustable in position to focus an image of a distant object in a plane j near a convergent lens i which concentrates the rays upon a number of lenses e each fitted with a colour filter and an iris diaphragm, and each of which projects on a sensitive panchromatic plate or film g in a holder h a separate secondary image formed from the primary image. The focal plane j of the objective a may be located behind the lens i and the primary image is focused either on a screen placed in the plate or film-holder h or on a removable screen placed at j and viewed in a reflex mirror seen through an aperture in the top of the camera, the mirror being swung into position when a flap closing the aperture is raised. Plano-convex lenses may be placed in front of the sensitive surface g to eliminate curvature of the images formed by the lenses e. The colour filters may also be situated in front of the surface g. After exposure and development, a diapositive is made from the negative, placed in the camera at h and illuminated from the rear with white light, and a ground glass screen is placed in the focal plane j whereby a reproduction of the object in natural colours may be viewed by looking directly through the objective a or may be projected upon a screen in front of the camera. A lantern for illuminating the diapositive comprises a multiple lamp with a group of condensers one for each element of the diapositive, or a single lamp p, Fig. 9, having a single condenser projecting light upon a group of converging lenses o each coaxial with the corresponding lens e. By placing an ordinary camera in front of the apparatus shown in Fig. 9, negatives may be made for the production of multi-colour printing plates by known processes. An apparatus comprising two identical cameras mav be employed for stereoscopic colour photography, the lenses e being placed in each camera at the vertices of a geometrical figure symmetrical about a vertical axis, and the figure in one camera being inverted with respect to that in the other, in order to produce a negative of the kind shown in Fig. 11 for three colours. In printing the diapositives, the groups of images are interchanged, the diapositive is inverted about a transverse axis before insertion in the viewing apparatus. In adapting the invention to a kinematographic camera, a complex objective comprising the objective a, lens i, and system of lenses e is employed in place of the ordinary kinematographic objective.