Movie Makers (Jun-Dec 1928)

photographer possessing no unusual scientific knowledge nor skill and it enables him to obtain photographic results nearing the coveted goal which can be expressed as "a perfection of photographic rendition which not only presents similarity of form with the object photographed, but also a color reproduction in conformity with the impression that each color makes upon the human eye." The problems inherent in panchromatic film are extremely complex if expressed in detail, but what precedes may be sufficient to give an idea of its reasons for existence and briefly answers the questions what and why? The next question is how? When an attempt is made to explain the functions of any human endeavor volumes could be written without exhausting the subject. The same applies to panchromatism as well as to any other step that marks progress in any art. It is the spirit with which the innovation is accepted that guides the true enjoyment in its use and therefore the true value of the innovation. Panchromatic film offers the possibility of more adequate and more artistic photographic results. The degree of artistic perfection is solely dependent upon the nature of the individual who is called to express it. The normality of results is purely physical and we shall confine ourselves to this material entity. In the first place, the amateur who is going to adopt panchromatic film should discard from his mind the thought that this film is more difficult to use than ordinary film. In the use of the two kinds of film there is the same necessity of protecting both from extraneous light and from undue exposure to excessive atmospheric conditions, such as excess of heat or cold and excesses of dryness or moisture. In regard to exposure to light, if panchromatic film should for any reason be unwound from its spool (which very seldom the amateur does (it must be unwound in complete darkness or under a special green light furnished by the film manufacturer. The reasons for this exceptional precaution are obvious when it is considered that this film is sensitive to all color radiations. If panchromatic film should be exposed in the dark room to the red light which has no effect on ordinary or orthochromatic emulsions it would be affected by the red radiations and fog would result, just as ordinary film would be fogged if unduly exposed to a light to which it is sensitive. The development of the image of the film so successfully carried on by the finishing laboratories frees the amateur from all the manipulations necessary in the processing of the film ALL THE TRUE BEAUTY OF THIS SCENE WAS RECORDED " ON PANCHROMATIC WITH PROPER FILTER and relieves him of the details that such processing involves. The concern of the amateur is then reduced to the matter of properly exposing the film so as to increase the chances of complete success in his undertaking. The main principles underlying the use of ordinary emulsions are to be applied to the panchromatic ones. The same judgment of the value of the intensity of the light and, therefore, the proper setting of the lens diaphragm is to be observed, as well as all other detailed precautions one has to keep in mind in any kind of photographic work, such as the focusing for the proper distance, the avoiding of the rays of the sun striking the lens directly, etc. The difference between ordinary and panchromatic films lies simply and solely in the difference of sensitivity for the different colors. In this respect it must be clearly understood that the sensitivity of panchromatic film represents an increase in sensitivity over the ordinary emulsions to the orange and red rays and not a diminution of sensitivity to the blue rays, so that panchromatic emulsions, while giving a brighter reproduction of the warm colors, still reproduce the blues as a range of grays much lighter than the visual interpretation of the blue colors. This result is untrue to nature and therefore unnatural. In other words, if no special precaution is taken, panchromatic film will give pictures very similar to pictures taken with ordinary emulsions and its use will not therefore be justified. It is evident then that if correct color rendering of the object is to be obtained the sensitivity of the film for the blue and violet colors has to be diminished. This cannot be accomplished in the preparation of the film and therefore the next expedient is to reduce the amount of blue light which concurs to form the image on the film. This reduction is obtained by filtering the light through especially prepared colored transparent sheets of gelatin or glass. All objects are seen by means of the light that they reflect and this reflected light is a composite of practically all of the colors that characterize the object itself. Blue light is existing in greater or less quantity in practically all the lights reflected from colored objects. It is well known, for instance, that a green paint is obtained by mixing a blue and a yellow paint. It is evident, therefore, that if such green paint is photographed so that the effect of the blue rays which it emits is over pronounced in respect to the yellow rays the green will appear photographically lighter than it appears to the eye. If this excess of blue is filtered out and an ordinary emulsion is used to photograph it the effect that the little amount of remaining blue and the yellow rays have on the emulsion is very slight, due to its lack of sensitiveness for the yellow part of the composite color, but as panchromatic emulsions are much more sensitive to the yellow rays than the ordinary emulsions the filtered light will have a much stronger and more prompt reaction on the film and consequently the exposure which is necessary for producing the reaction is greatly reduced. Now, we can consider any scene as composed of an innumerable quantity of different colors which react on the film according to their particular hue and brightness. By filtering out the excess of blue light from all of these colors a truly balanced exposure will be secured from each one of them and a 585