Journal of the Society of Motion Picture and Television Engineers (1950-1954)

ments of mechanical objects can be studied with lower repetition rates. However, the new Isotran camera is expected to have many applications in the study of movements of miniature mechanical parts. An inverse relation only now becoming recognized is the one existing between the size of a physical object and the repetition rate needed to clarify its movements at a given velocity. Even when moderate linear speeds are involved, repetition rates are needed in the range for which the new Isotran camera was designed in the study of phenomena such as the formation of chips by a cutting tool, the cutting action of an abrasive particle, the motion through air of droplets of liquid, the action of the breach mechanism of a small gun, the operation of miniature high-speed gears and ball bearings, the spinning or drawing of fine artificial fibers, and the transference of ink or other material from the surface of a high-speed roller. The new Isotran camera offers the possibility of studying these largely uninvestigated phenomena, and offers for this purpose resolution adequate for most needs. The camera, however, is not intended to be competitive with those commercially available for use in the speed range now covered by them. References 1. C. D. Miller, "40,000 frames per second," PSA Jour., 74: 669-674, Nov. 1949. 2. C. D. Miller, "The NACA high-speed motion picture -camera-optical compensation at 40,000 photographs per second," National Advisory Committee for Aeronautics, Report No. 856, 1946. 3. C. D. Miller, "Roles of detonation waves and autoignition in spark-ignition engine knock as shown by photographs taken at 40,000 and 200,000 frames per second," SAE Quarterly Trans., 7: 98143, Jan. 1947. Discussion Carlos Elmer (Naval Ordnance Test Station j\ China Lake, Calif., and Chairman of theSession): Can these photographs be printed* iri4 motion picture form? Mr. Miller: The photographs are ready for projection as a motion picture as theyj come from the developer after removal from the camera, and they project verjH steadily on the screen. Anon: How is the film taken up fromi the drum onto the spool? Mr. Miller: The film is placed in one continuous strip around the inside of thd ledge on the side of the drum. We take photographs only for the time required for one complete turn of the drum. The drum is brought up to speed; then a shutter at the objective lens is opened. The shutter stays open for approximately the time required for one complete turn of the drum. The film is placed in the camera by hand, through the handhole, and is held in accurate position by pegs in the ledge of the drum, one peg for every ten perforations of the film. Earl A. Quinn (Eastman Kodak Co., Rochester, N.Y.): It appeared to me from your drawings that the film was on the opposite side from the prisms. Is that true? I understood you to say it was on the same side. Mr. Miller: Yes and no. In the earlier form of the camera, in the laboratories of the National Advisory Committee for Aeronautics, the prisms and the film were both on the inside of the drum, and the light went across the drum in passing from the prisms to the film. However, in the form of the camera I have described here, the film is on the inside of the drum and the prisms are on the outside. Instead of passing across from one side of the drum to the other, the light follows a circuitous path, from the prisms on the outside of the drum to the film on the inside, but with the same angular position for prisms and film as measured around the periphery of the drum. 144 Jebruary 1953 Journal of the SMPTE VoL 60