American cinematographer (Jan-Dec 1926)

Twenty-two AMERICAN CINE MAT OGRAPHER July, 1926 with constant agitation and to use as dilute a stock solution as is convenient. When a precipitate once forms because of a high local concentration it dissolves very slowly, if at all. We have never been able to prepare successfully a phenosafranine-hydroquinone developer as frequently recommended jn the literature. 2. Effect of Concentration and Time of Bathing on De sensitizing. With pinakryptol green and most other desensitizers the effectiveness is greatly increased by the presence of the developer and therefore the concentration of dye required is much less than when used in a water solution. In Figs. 4 and 5 curves are given which show the comparative desensitizing action of pinakryptol green in different concentrations when used in the developer and in a preliminary bath. From these curves it is evident that a concentration of 1-25,000 in an elon-hydroquinone developer produces more desensitizing in a given time than a 1-5000 solution in water. In view of this fact Hubl ' has suggested that development be started with an old developer containing desensitizer and completed in a fresh developer without desensitizer. He also states that after a preliminary bath the desensitizing is increased when the film is put into the developer rather than the dye being washed out. This, of course, does not apply to desensitizers which are made inactive by sulphite. 3. Limits of Safety in Exposing Desensitized Film to Different Safelights. In Table II data are also given which show the safe time of exposure to different safelights after desensitizing with different concentrations of pinakryptol green in the developer. It can be seen that panchromatic film can easily be made safe for the bright green light Series 4, but not for bright red lights. Motion picture negative film, on the other hand, can easily be made safe for the Series 0 or even Series 00 safelight. 4. Fogging Action of Pinakryptol Green when used in the Developer. It is stated by the manufacturers of pinakryptol green that it diminishes development fog, and a similar effect was found by Amor4 for several desensitizers. The effect of pinakryptol green added to the developer in concentrations between 1-25,000 and 1-100,000 was studied for several different developers, including glycin, rodinal, elon, elon-hyroquinone and pyro. Motion picture negative film was used. In most cases it was found that both the development of the image and the growth of fog were retarded. The effect of shortening the induction period is the same as when used as a preliminary bath. However, for the same image density in most cases the fog was slightly less when desensitizer was present. The decrease in fog density varied from 0 to 0.04 with different developers for normal development, and was not therefore of sufficient magnitude to be of very great practical importance. In no case was any serious fogging action detected when the dye was used in the developer. 5. Comparative Desensitizing Action During Exhaustion of Developer. In order to find whether the desensitizer in a developer was effective throughout the life of the developer, solutions containing 1-25,000, 1-50,000, and 1-100,000 of pinakryptol green in MQ Tank developer were exhausted. _ Over a period of 10 days one E. Burton Steene Freelance Akeley Camera Specialist GRanite 1622 Care of American Society of Cinematographerg 1219-20-21-22 Guaranty Bldg. Hollywood, Calif. FOR RENT! MITCHELL and BELL & HOWELL CAMERAS F 2. 3. F. 2. 7. F. 3. 5. Lenses 40-50-75 M. M. COMPLETE EQUIPMENT J. R. LOCKWOOD 523 North Orange St. Phone Glendale 3361-W Glendale, California CRECO FOR SALE OR TRADE 4500-Watt E. U. Type De Vry Portable Projectors, like new. 1 Universal and 1 Precision Tripods. HERBERT GEORG STUDIO 514 East Capitol Avenue Springfield, Illinois SUBSCRIBE FOR THE American CinematoqrapKer I HARRY D. BROWN Cinema Studios Supply Corp. 1438 Beachwood Drive HOIIy 0513 » . ft HOI|y 0514 Brown-Asncraft Studio Lamps Carbons, and Other Studio Equipment mirV