The international photographer (Jan-Dec 1931)

March, 1931 The INTERNATIONAL PHOTOGRAPHER Five Allen C. Jones Jerome H. Ash Paul H. Allen Sol Halprin L. T. Galezio Ray Wilkinson Paul P. Perry W. G. Thompson John Arnold Sol Polito John J. Mescall Jules Cronjager William V. Skall Virgil Miller Mack Stengler W. H. Tuers Gil Warrenton W. L. Marshall Paul G. Hill Ira B. Hoke Ernest Miller Dewey Wrigley Pliny W. Home Jack R. Young Barney McGill Tony G. Gaudio E. t. Estabrook Harry Jackson Raider B. Olson R. E. Lyons Faxon M. Dean Harry Perry V. L. Walker R. B. Staub Frank Cootz Charles Rosher Paul E. Eagler Roy Davidge Hal Hall Fred W. Gage Harris Ensign Charles Levin Alvin Wyckoff George Blaisdell C. Roy Hunter Fred Jackman Len Powers H. N. Kohler J. A. Dubray G. MacWilliams Charles Stumar E. J. Snyder Earl R. Hinds Ira H. Morgan J. E. Tucker Irving G. Ries Harold Lipstein John F. Hickson R. V. Doran Wiliam A. Rees Lenwood Abbott Ernest Palmer Jackson Rose Arthur L. Todd W. E. Fildew Theo Sullivan Rex L. Wimpy H. Knollmiller R. B. Nichol John S. Stumar Joe J. Novak Ben H. Kline L. L. Lancaster Robert M. Pierce Frank H. Booth Wilson Leahy Eddie Kull Jack Fuqua W. C. Thompson Perry Evans F. E. Larkin J. M. Nickelaus Mike Leshing T. M. Ingman A. J. Guerin Joseph Aller Ray Mammes Park J. Ries C. E. Van Engler Harry Gant Dodge Dunning Ted McCord M. B. DuPont C. M. Downer Edwin O'Connell C. S. Piper Harry Vallejo Bill Eglinton Frank M. Cotner Victor Milner L. W. Physioc E. S. Depew Roy Purdon H. F. Koenekamp R. E. Yarger Dev Jennings W. V. Kelley Nick Musuraca J. W. Howe Leon Shamroy Percy Hilburn Arthur Martinelli Paul Lang H. L. Broening C. E. Schoenbaum George Seid Jake Badaracco Farciot Edouart Ray Rennahan J. H. August Henry Goldfarb Otto Himm G. Schneiderman George Crane Andre Barlatier J. C. Van Trees Harold Rosson Milton Cohen Karl Freund W. Crespinel Eastman Super Sensitive Panchromatic Type Two — Motion Picture Film By EMERY HUSE and GORDON A. CHAMBERS West Coast Division — Motion Picture Film Department Eastman Kodak Company ON February 5, 1931, the Eastman Kodak Company announced to the motion picture trade in Hollywood its new super sensitive panchromatic type two motion picture negative film. Inasmuch as this film exhibits characteristics not hitherto shown in motion picture negative emulsions it was considered advisable to present some data pertaining to those characteristics. This article is not presented as a complete technical treatise of the characteristics of the super sensitive film, its aim being to call attention briefly and simply to the differences this super sensitive film exhibits over the present type of panchromatic films. As the name super sensitive implies, this emulsion is extremely fast, but because of its name this new film must in no way be confused with a hypersensitized film. In the past when an emulsion of extreme speed was desired, either for color photography, filter shots or trick work, it was customary to especially treat the film with some type of sensitizing bath. This bath caused a general increase in the emulsion speed and particularly increased the red light speed. However, the hypersensitized film had certain disadvantages such as its cost, its lack of keeping qualities, and its propensity to produce fog. With the super sensitive type two these disadvantages are entirely overcome. The increased speed of the super sensitive film has been accomplished during the course of the emulsion manufacture. It is sufficient to say, therefore, that the super sensitive film is not a hypersensitized film. Furthermore, the super sensitive film exhibits the same keeping qualities and shows identical physical characteristics as those shown by the present panchromatic films. Greatly Increased Speed A complete study of any type of film emulsion is best accomplished by making both sensitometric and practical camera tests. This article will not deal in any detail with camera tests but will consider in some detail the sensitometric characteristics oi the super sensitive emulsion as compared with the present type of panchromatic film. The point of major importance in the consideration of the super sensitive film pertains to its greatly increased speed. The data obtained sensitometrically can be and have been checked by camera exposures. Sensitometry involves a study of known values of exposure as related to the amount of silver (density) which these exposures produce upon the film after development. The standard sensitometric curve is therefore one in which is shown the relationship between exposure (expressed logarithmically"1 and the densities produced. It is from curves of this type that the sensitometric characteristics of the films under investigation have been studied. Another important consideration in studying the speed of the super sensitive film necessitates a study of the quality of the light sources to which this film is exposed. For that purpose sensitometric tests have been made to daylight and to tungsten. Inasmuch as the mode of testing an emulsion to any light source is practically identical we shall for the sake of brevity and clarity consider only the curves obtained by exposure to tungsten. Defining Speed Figure 1 shows the sensitivity curve of the present and super sensitive type of film for tungsten exposures developed for a fixed time, nine minutes in a standard borax developer. It will be observed that the supersensitive curve lies above the curve for the present type of film, and the separation of these curves gives an indication of the speed difference existing between the two films. In making a numerical estimate of the speed we do not consider the actual density values produced for a given exposure. The customary method is to deduce speed from the exposure value obtained at the point where the straight line portions of these sensitivity curves, extended, intersect the exposure axis. Speed is usually defined by the following formula: 1 X C =: Speed, i where i, the inertia, is the exposure value of the intersection point and C is an arbitrarily chosen constant. For the curves shown in Figure 1 we find that the speed of the super sensitive film, as represented by curve No. 2, is three times that for the present type films. Identical tests made to daylight show that the super sensitive film is twice the speed of the present type. With reference to Figure 1 attention should be called to the marked difference in the low exposure region, that is in the toe of the H and D curve. In this region the super sensitive film definitely differentiates between exposures of very low intensities. Particular reference is made to the exposure region to the left of the relative log exposure value of 0.3. Tungsten Speed Greater The cause for the difference in relative speeds between the two types of films to tungsten and to daylight, or to any other source, is entirely dependent upon the color distribution of light from the source and its effect upon the color sensitivity of the emulsion. It is generally known that tungsten, for example, contains a greater pro EXP0SURE : TOMGSTEN S Min. in Borax i. Present Films z. Super Sensitive Film "Relative Log E o.o oS oS 55 Ti is i* u S» TT Figure 1