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

[photography, for high-grade motion picture work, and for many specialized photographic processes has sharpened the debate and brought into much clearer focus the relation between the light distribution of the original scene and that of the final photographic product. Mr. Dunn's book makes available to the working photographer, amateur or professional, a single source describing virtually all the equipment and techniques for determining exposure. A chapter on the fundamental theory of exposure requirements presents an informative discussion of the derivation of film speed ratings, the criteria of correct exposure, and the methods of assessing the subject lighting, including brightness measurements (highlight, shadow, average, and "keytone") and "incident light" evaluation. Chapters on exposure tables and calculators, extinction meters, photoelectric integrating meters, photoelectric incident light meters and exposure photometers include detailed descriptions of most available commercial equipment (European and American). Useful intercomparisons of the results obtainable and the uses, limitations, and precautions to be observed in each case are provided. Throughout the book, the differing requirements of still monochrome photography and motion picture and color work are emphasized. Many tables are included, such as film speed ratings, comparisons of various speed rating systems, etc. Most of the working data that involves speed ratings is presented in a double notation giving the B.S. (British Standards Institution) and A.S.A. ratings side by side. The exposure tables however are presented for use with the B.S. ratings only. American readers will prefer equivalent tables based on A.S.A. ratings, such as the A.S.A. Photographic Exposure Computer for daylight photography, but may find it worth while to convert to B.S. ratings in order to make use of the excellent tables for photography by artificial light. Only a very few minor criticisms might be made of Mr. Dunn's book, and these do not detract from the general excellence of the presentation. The author has gone too far in an effort to substitute nontechnical language for relatively simple technical concepts. I suspect for example that the use of the term "kissing" for "tangent" would be more likely to involve the reader in speculations as to the aptness of the metaphor than it would be likely to clarify the concept of tangency. In discussing the variation of light output of incandescent lamps with voltage (in a table on page 83 and in connection with the calibration of exposure meters on page 129) the actual voltage variations are used rather than the percentage variation. Inasmuch as the lamps described are operated at about 230 volts, the voltage figures as given are not valid for lamps operated at 115 volts or lower. If the variation had been given in per cent, the data would be sufficiently accurate for lamps operated at any voltage. Although exposure tables and calculating devices are described extensively, tables of "guide numbers" commonly used at least in the United States with photoflood and photoflash light sources are not mentioned. Mr. Dunn devotes considerable space to a description of exposure photometers, particularly the SEI meter, for which he is so largely responsible. It should be noted that although his perhaps pardonable enthusiasm for this instrument colors the parts of the book in which its construction and use are described, it has not affected the sections dealing with other types of instruments, which are described fully and fairly. Whether the reader is already committed to using a particular kind of exposure meter, or wishes to determine what meter to obtain or what techniques to use, or even if he is not interested in a meter at all and wants only a general understanding of the problem together with a set of useful tables, he will find the book instructive and helpful. — Theodore H. Projector, National Bureau of Standards, Washington 25, D.C. A new edition of the Society's Test Film Catalog is now available at no charge from the Society's headquarters. It covers 27 different test films, 16mm and 35mm, for use by theaters, service shops, factories and television stations. These test films have been developed by the SMPTE and the Motion Picture Research Council. 199