Abstract
AN interesting demonstration was given on June 12 of a new development in the taking and timing of serial photographs of objects moving at high speed. The apparatus, which is easily portable, is the combined work of the Western Electric Co. and Kodak Limited. It was demonstrated that 2,500 exposures per second could be made of objects in normal daylight or illuminated with ordinary ‘½-watt’ type lamps on the standard small size Kodak film. The interest in the camera lies in its extreme simplicity. As the film has to move across the focal plane with speeds up to 50 feet per second, the usual intermittent motion must be dispensed with and a uniform motion substituted. Mounted between the lens (Kodak anastigmat fI-8) and the film is a small slab of glass which rotates about an axis parallel to its own plane and passing through the middle of the slab. This gives a lateral motion to the image in the same direction as that in which the film is moving. Exposure is only allowed when the slab is approximately normal to the, when the lateral speed of the image will be ωT (μ-1 )/μ,where T is the thickness of the slab and ω its angular velocity. There is no mechanical shutter other than the mounting of the slab, which intercepts the light twice for every complete revolution, and this combined motion of film and image takes the place of the more usual motion hitherto adopted. The image of a moving dial is projected on to the corner of each exposure by an accessory internal optical system. The motion of the dial is controlled independently by a 200-fork controlling a synchronous motor. The time spacing on the image can be read to 1/1000sec. demonstrations of muscular reaction times and of splashes were extremely good, but it was noticed that in the comparatively simple image of a falling steel ball, there was a slight elongation.
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High Speed Precision Photography. Nature 133, 902–903 (1934). https://doi.org/10.1038/133902d0
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DOI: https://doi.org/10.1038/133902d0