The Cine Technician (1953-1956)

80 THE CINE-TECHNICIAN July, 1953 As to glare, a curved screen produces more, not less, glare. " 3. Illusion of Depth. No data advanced by the proponents of curved screens — nor, for that matter anything in the literature of the art prior or present — lends any credence to the assertion that a curved screen contributes in even the slightest degree to an enhanced illusion of depth. " 4. Sound Transmission. The assertion that a concave screen improves sound transmission is just not true ... all screens impair sound transmission to a certain measurable extent, and the curved screen is neither better nor worse in this respect. " 5. The Keystone Effect. Elongation of the projected image is caused by steep projection angles. The same is true of ' keystoning ' . . . with its characteristic convergence of vertical lines towards the top. These deficiencies could be corrected somewhat by tilting a flat screen to a suitable, but impractical, angle. ... A curved screen cannot eliminate keystoning except at certain places where the curvature assumes the same impractical angle. " 6. ' Can be washed like glass.' This is a false and wholly misleading statement. With ordinary glass, dirt which gathers on the surface may be rubbed off. The curved screen consists of a grouping of glass threads between the fibres of which dirt collects. As with any fabric, the dirt must be washed out by laundering." /COLUMBIA Studios' 3-D Camera, designed and ^ built under the supervision of Gerald Rackett, is the camera which has been widely publicised recently as being capable of shooting 2-D, 3-D and wide-screen pictures at choice. Basically the set-up consists of two Mitchell cameras mounted side by side — no mirrors are employed. One camera is inverted to bring the lenses into the close proximity necessary, but the film magazines of both units are on top. The cameras are mounted on base plates which allow them to be moved in and out of the blimp at the rear for inspection and loading. By racking over the two cameras — one to the left, the other to the right — two viewfinder tubes can be inserted between the cameras to permit binocular viewing of the scene through the camera lenses. This enables the cameraman to line up his shots for correct convergence and interaxial spacing. This operation is carried out by placing a marker pole in the set at the point where the lenses are to converge; when the cameras have been lined up the finder tubes are removed and the cameras racked over to taking position. The alteration of convergence is achieved by mounting one camera so that it can rotate on its base in a limited arc. Convergence, lens separation and focus are controlled by shafts extending from cameras to outside the blimp. The lens mechanism of the two cameras is synchronised and interlocked for follow focus on moving camera shots. The Mitchell finder is fitted with a combination mask which defines both the standard aperture and the new 1.85 to 1 ratio which Columbia has adopted for its wide screen standard. No mirrors or prisms are used : hence both nega{Continued on next page) New Frames for Old ^^%^2 -o J^X*^ These four enlargements of negative show the boundaries within which oil important octton has to i>< kept for v, innus aspects ni wia» screen. 1.376 to 1 corresponds t» the existino standard of 4X3 and requires a projector aper titn /ilate'ot .825" v.60li". 1.666 to 1 {standard of 5X3 «>!</ aperture plate .825"x.495">. 1.80 to 1 (5JX3. aperture plat' .825"X.443"). 2 to 1 (6X3) aperture idatt .826"X.412". CinemaScopt luol illustrated here) has a slumlord of 8X3 with an aspect of 2.6 to 1. but compression permits the us, o] a normal apertwn plate of .825"X.600". Courtesy, Kmt u< i /.///