British Kinematography (1950)

190 BRITISH KINEMATOGRAPHY V01. 17, No. 6 way as a negative. The things that are used and seen, and on which the films are judged, are the prints. It is, therefore, of great importance to discover the characteristics required in the original in order to get the best prints. In printing a reversal duplicate from a master original Kodachrome film, two things occur : the contrast is increased, and at the same time the colour saturation is decreased. We must therefore aim in the original at less contrast and more colour saturation than is wanted in the print. This means in practical terms that the contrast range must be carefully controlled within the limits of toleration of the film. The full contrast range of the film must not be made use of as if only the original were being produced. Contrast Range. It has been stated that the contrast range of illumination as between shadows and highlights for Kodachrome should not exceed 4:1. My own experience is that this ratio can safely be exceeded, and be as high as 5 : 1 or even 6:1, where originals only are required. For successful printing, however, the ratio of 4 : 1 should not normally be exceeded, and in certain cases should not exceed 3:1. Let one point be made clear, however ; a normal picture is being discussed where it is desired to see detail in both shadow and highlight. There are occasions where, for dramatic or other reasons, this recommendation can, and sometimes should, be ignored. Further, it is necessary not to confuse contrast range with brightness range, which owing to light absorption by certain coloured objects in the scene may be considerably greater than the contrast range. Secondly, to obtain an acceptable print, it must be ensured that the original has enough colour in it. Fortunately, this is quite easily done by slight underexposure, and my own recommendation is that one should under-expose by about a half stop compared with what would be done were a first-class original desired, though again this is a matter of opinion. It all depends on what result is being aimed at ; whether a " high key " result (or as high a key as one can get in 16mm. colour) or " low key," and whether the subject is light in character or dark. Assessing Exposure. In this country 16 mm. Kodachrome film is marketed in two grades. — Regular, which is intended primarily for use in daylight (590CTK-6300oK. a mixture of clear sun and skylight) and Type M A," which is designed primarily for use with Photoflood lamps (approx. 3350CK) ; the appropriate grade according to what is to be undertaken will naturally be selected. Before discussing light sources and their attendant difficulties, I would like to say a little more about exposure.5 It is usual to use some form of photoelectric meter, though for daylight, the Kodak tables supplied with the film are remarkably useful and should not be despised. After some trials, I have come to the conclusion that a highlight method, measuring the light falling on a standard card, gives the most satisfactory results. There is no need to use a white card ; a neutral shade is, in my opinion, better, and this need not even be the same on every job, since one will always wish to carry out tests on each emulsion of film used. One of my colleagues obtains best results by using the S.E.I, meter, in conjunction with a white card, since this enables the contrast range between highlight and shadow to be measured more easily. Others use a Weston meter with equal success. Some have developed the knack of measuring high-lights only and judging the shadows by eye. When this is done a monochromatic viewing filter is a useful accessory. Whatever is done, if one is doing this sort of thing daily it is rare to make a mistake in exposure. Test Films. The making of tests before embarking on a job has been referred to. It is common practice with many to carry out tests with black-and-white emulsions ;