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Report of the Progress Committee 71
twenty years. ^^ Focal lengths of the taking lens affect the perspective of the projected picture, occasionally introducing serious distortion. The use of large aperture lenses has been reviewed and it is claimed that such lenses are unsuitable for portraiture at distances shorter than about 15 feet.^^ A new f/1.4 objective for cine cameras has been announced which has six elements, two pairs of which are cemented.^^ Several patents^^ on objectives of various types have been taken out related to panoramic work, stereoscopic effects, non-intermittent movements, and alternate use of one of a plurality of lens systems.
The advantages and limitations of various shutter designs have been discussed. ^^ Another article dealing with theoretical and practical considerations of the design of claw pull-down movements is of interest.**^ A shutter claiming to reduce flicker and eliminate scattered rays has been patented*^ and has an oscillating beater type of pull-down that makes a friction contact with the film just below the gate.^^ A few additional patents have been issued on various types of pull-down mechanisms.^^
Cameras and Camera Accessories. Newman** has designed a light, automatically driven camera of 200 feet capacity which is claimed to run 160 to 180 feet at one winding of the spring motor. A new camera for both normal and high speed exposures has been developed which carries 25 meters of film, has a 170° shutter, and a hand or spring drive exposing 16 or 50 frames per second.*^ Of historical interest is the description of a camera designed in 1897 to take 100 pictures per second.**^ The film had no perforations and was moved by a rubber friction roller which rotated in one direction and then reversed for a very short time to stop the film. Thun*^ has given a very brief description of his speed camera capable of taking 2,000 pictures per second. Midday sunlight exposures have been obtained at -8-15 feet under water with a De Vry camera enclosed in a metal waterproof box.*^ Two new Debrie cameras have been described recently before the Society, one for high speed use and one for professional and news work.*^ To silence the Bell & Howell camera for sound work, fiber gears have been introduced and the film tension set at from 1-1/2 to 2 ounces. A belt tightener was incorporated insuring even take up and bronze substituted for ball bearinors.^^