Journal of the Society of Motion Picture Engineers (1930-1949)

size. The result is finally reproduced in the form of graph paper for locating and recording the data or objects. The new 12.7 mm //1. 5 Cine Raptar for 16mm cameras has been designed to fill the need for a distortion-corrected lens with minimum residual aberrations where extreme coverage is not a primary requirement. It has a diagonal coverage of 56°. In addition to the basic lenses and lens mountings required, special attention has been given to the varied needs of the users. The most frequent requirements are for compensation of focus shift with temperature changes, and for reticle reference-marking attachment. Normal focus shift with temperature changes may be accomplished by a calibrated air-space change between favorably disposed elements of the system, or by spring-loading the elements of the system against suitably placed invar rods. The method used is determined by the lens design. The correction of focus shift with temperature is most necessary for long focal length lenses. Many applications of high-speed motion picture photography in the field require a reference mark within the picture area. This is accomplished with an optical reference-marking attachment whose residual aberration contributions to the primary lens must be kept at a minimum. The optical reference-marking attachment is composed of a cross-line engraved field lens and a high-aperture lens which images the cross lines and the image due to the primary objective on the film at 1:1 ratio. This attachment is par-focussed and can be used with any of the high-speed motion picture camera lenses, and can be adapted easily to other applications. A means for focussing the lenses is often required and provision is made for focussing the majority of the lenses wherever it is required. There is also some demand for viewing devices through which it is possible to follow the action being photographed. Where required, such devices can be manufactured and supplied. Every attempt has been made to supply to the user in the field a wide variety of lenses, devices and aids to simplify and expedite his work, which is so essential in the common defense effort today. References 1. B. Schmidt, "Ein Lichtstarkes Koma Freies spiegel system," Mitteilungen Hamburger Sternwarte in Bergedorf (Reports of the Hamburg Observatory in Bergedorf}, 7: 15-17, 36, 1932. 2. A. Bouwers, Achievements in Optics, Elsevier Press, 402 Lovett Blvd., Houston 6, Tex., 1946. 3. D. D. Maksutov, "New catadioptric meniscus systems," J. Opt. Soc. Am., 34: 270-284, May 1944. 4. K. Pestrecov, "Resolving power of photographic lenses," PSA Jour., 13: 155-158, Mar. 1947. 5. K. Pestrecov, "Resolving power of photographic lenses," Photogrammetric Eng., 13: 64-85, Mar. 1947. 6. F. H. Perrin and H. C. Hoadley, "Photographic sharpness and resolving power," J. Opt. Soc. Am., 38: 10401053, Dec. 1948. 7. Paul L. Pryor, "Air Materiel Command research on resolution and distortion," Photogrammetric Eng., 12: 89, Dec. 1946. 8. C. W. Kendall and B. A. Schumacher, "Measuring the resolving power" of lenses," Photo Tech., 3: 51, Apr. 1941. 9. L. E. Jewell, "A chart method of testing photographic lenses," J. Opt. Soc. Am., 2-3: Nos. 3-6, 51-61, May-Nov. 1919. 10. L. E. Hewlett, "Photographic resolving power," Can. J. Research, Sec. A, 24: 15-40, Apr. 1946. 11. M. Herzberger, "Light distribution in the optical image," J. Opt. Soc. Am., 37: 485-493, June 1947. 12. O. H. Schade, "Electro-optical characteristics of television systems: Introduction," RCA Rev., 9: 5-37, Mar. 1948. Gilkeson and Turula: Optical Aids 501