Patent GB-524381-A (GB)
Title: Improvements in colour cinematography
IPC: G03B33/00
Filed: 1938-10-27
Abstract: 524,381. Colour kinematography. COSMOCOLOR CORPORATION. Oct. 27, 1938, No. 31141. Convention date, Oct. 27, 1937. [Classes 97 (i) and 98 (ii)] In apparatus for projecting into superposition two colour-record images arranged side by side and side uppermost in each image space on a normal kinematographic film, and comprising separate projection lens systems, one lens system is wholly fixed and the other is wholly adjustable in two directions for superposing the projected images ; an axially movable septum may extend from the film to a position between septums separating the lenses, baffles may surround the light path to prevent reflection of stray light, particular colour filters may be used, and means for quickly and easily positioning the carrier for the lens system &c. in a projector may be provided. The optical elements are as described in Specification 489,333, and comprise completely separate objectives 44, 45, Fig. 8, and colour filters 47 in the rear part of a cylindrical casing 32, and an erecting prism system, which may consist of a single Dove prism 72, Fig. 12, in place of the separate Dove prisms described in Specification 489,333, in the front part of the casing 32. The casing 32 is provided with a spring-pressed telescopic hood 31 having openings which are forced into engagement with the projector gate and are separated by a septum 54 having a warped end entering between fixed septums 52, 53 separating the objectives 44, 45. The objectives are respectively carried by a fixed support 35, Fig. 12, and by a support 55 movable vertically on a member 56 which is movable horizontally on a prism-retaining frame 57; a spring retaining ring secured to the support 35 holds the members 55, 56 against the frame 57. The objectives may be differently spaced from the film in accordance with the light values of their associated colour filters. Movements of the members 55, 56 are effected by eccentric ends on rotatable rods terminating in finger levers 62, 63, Fig. 1, and passing through holes 64, 66, in the member 57 to engage respectively in slots 68, 65 in the members 55, 56 ; a slot 67 in the member 56 permits passage of the rod entering the slot 68 without restriction of lateral movement of the member 56, adjustable braking means bears against the levers 62, 63, a cork member 73 assists in retaining the prism 72 in place, and light baffles 72a of sawtooth section are formed in the light opening of the member 57. The casing 32 &c. may be fitted in a projector comprising a single lensclamping ring 97 by freeing the clamp, removing the lens, and inserting the casing 32 therein. To facilitate positioning of the casing 32 so that the reflecting surface of the prism 72 is at 45 degrees to the horizontal, an annular member 87 having a forwardly extending lug 88 is provided on the projector. A clamp 89 is permanently fitted on the casing 32 and carries an arm 91 which is shaped to fit the lug 88 and is fitted with a spring-pressed bolt 92 to engage a threaded hole in the lug 88. A modification is described comprising an adapter shell fitted to the casing 32 and facilitating positioning &c. in a projector comprising two lens-holding clamps. The filters 47 may be Nos. 28 and 38, respectively cine red and toluidine blue, in the series sold under the Registered Trade Mark " Wratten," and the original negatives may have been exposed respectively through a No. 22 filter, and through a No. 59 filter in sunlight, a No. 59A filter in incandescent light, or a No. 60T filter in arc light. Specifications 102,280, 256,449, [both in Class 97 (i)], 459,333, [Group IV], and U.S.A. Specifications 1,262,954 and 2,050,224, also are referred to.