International Review of Educational Cinematography (Jan-Dec 1934)

TECHNICAL FILM PROBLEMS 307 protected from the light is placed in a box, in which it is subjected on all sides to the light of several lamps. Afler the exposure, the development is carried out to that degree necessary for darkening the silver bromide that creates the image, eliminating the excess afterwards with hyposulphite. Besides being complicated, this method has two serious disadvantages. (1) It is very difficult to obtain a uniform exposure of the film in every part. (2) It is possible to correct errors of exposure which affect the entire film, but not errors which are only partial and limited to a section of the picture-making. The problem of how to handle inverted film has, we may say, been solved, by means of the second exposure regulated automatically according to the opaqueness. It is by means of the photo-electric cell that we can measure such opaqueness and regulate the intensity of the illuminant. It can be seen that in this fashion we can correct even considerable errors in exposure because if the residual image after the inversion is exaggerated, the lighting will be automatically limited to a portion of the stratum necessary to give the requisite intensity in subsequent development. Experiments with Wi I des ired to observe the dely varying Expo possibilities for correcsures carried out don whkh g mm fiJm on 8 mm film and a i j . „ _, oners when exposed automatically De , , . , under greatly varying conditions, with the second exposure automatically regulated. I used the Cine Kodak N° 8, which is a handy and perfect apparatus. The film used was Kodak super-sensitive panchromatic, which in the cinema industry is, we may say, the only film used, since it is the most sensitive to the light of incandescent electric lamps which form the chief illuminant in studios. Panchromatic film, intended for substandard cinema cameras using 1 6 mm and 8 mm reels, has probably the same emulsion as the Kodak industrial film, for the Kodak people have been able to increase greatly the ordinary and chromatic sensitiveness of the film without increasing the grain as compared with the old type film, indeed diminishing it. This film, treated with an appropriate bath, will allow of a development suitable for the successive inversion. The automatic machine which Kodaks have produced for the development and inversion of 16 and 8 mm films is not known in its particulars .being in the nature of a trade secret. . It is known that after the first development and inversion, every section of the film is, so to say, explored in its opacity by means of a application of the photo-electric cell sensitive to red light. The cell commands the resistance of the lamp which has to impress the bromide of silver for the second exposure. After the second exposure, and the second development, the excess of bromide of silver is eliminated by fixing. Films which a colleague of mine exposed under varying conditions (one film shows some interesting episodes of the palio of Siena) were of necessity handed to the Kodak firm for development and inversion and returned ready for projection. It was a great revelation for me to observe the perfection of the pictures. Proportionately, as compared with normal theatrical film, the projected image was larger, and in detail, modelling, absence of grain, sharpness and transparency it was such as to make one think that cinematography with substandard, reversible film is today able to compete with and in certain cirsumstances to be superior to ordinary normal size theatrical film. Indeed, when we are dealing with negative film, we are very far from being able to make such important corrections in the wrongly exposed sections of film, and it is inevitable that we find in the negative images differing in intensity and contrasts. This disequilibrium cannot ever be remedied in the positive print as it is in the direct automatic control development of the positive film. Moreover, as I have already said, the grain of the image is superior as is also the detail, which is