International photographer (Jan-Dec 1941)

l6MM. dcpARTMEIMT Some Additional Notes on Kodachrome In our article last month on Kodachrome, appearing in these pages, we purposely avoided the discussion of filters for use with this medium, deciding to treat this in an article by itself. Filters, used with Kodachrome, have the ability of not only adapting the exterior-balanced emulsion for interior work, and vice versa, but also that of taking a variety of different color-temperatures of light and giving a final result of color balance and tone that is as consistent throughout scene after scene as though they had been photographed under one correct lighting condition. The two devices necessary are a color temperature meter, and a set of color compensating filters that Eastman puts out. The meter, if carefully used and corrected for the color sensitivity of the eyes of each individual, will accurately measure the temperature in degrees Kelvin. This business of color temperature might sound like a complicated affair to many amateurs; all that it is, is a "yardstick" placed against a color chart to give a definite number to that particular color so that we may duplicate the exact color of a given number. The need for this sort of system for purposes of correction will become apparent when we examine the delicate color sensitivity of the modern Kodachrome emulsion. Couple this with another fact: Most of us have noticed how with ordinary electric light bulbs one of them may seem particularly yellow, or another rather white in light. This has nothing to do with the amount of light, because an automobile headlight having only a candlepower of 32 or so may be considerably whiter than a house light of several hundred candlepower. This difference in color — or, specifically, color temperature — will photograph correspondingly. The emulsion balanced for artificial illumination (Type B) is balanced for photofloods. Photofloods have a measurable color temperature of around 3400 degrees Kelvin, depending on the voltage of the line, since the color temperature of a photoflood will vary roughly about five degrees per volt. (The term "Kelvin" is used CINEX Light Testers — Polishers used by all Major Studios. We are the sole Manufacturers and Distributors. Manufacturer of 16mm and 35mm Recording Heads, Developing Machines, Bipack Color and Black and White Printers, Rewinds. Special Machinery built to order. CINEMA ARTS-CRAFTS 914 No. Fairfax HE 1984 Hollywood, Calif. Cable Ai).lre«»: "CINEBARSAM" 20 in the same sense as Fahrenheit, or Centigrade, Kelvin being the scale which has for its zero point "absolute zero," that point at which all molecular activity ceases. ) The color temperature of a standard mazda will run from 2800 degrees to 3250 degrees, latter being intended for color photography. The color temperature of the light encountered on exteriors will be in the neighborhood of 5,000 degrees K. And since the Type B is balanced for 3,400, as noted above, it is evident that the wide variety of illumination that is apt to be encountered in the course of work with this medium will result in serious inconsistencies in the finished film unless some means are used to equalize these conditions. The color compensating filters mentioned above are intended to do this. Where the light is too blue they will hold back enough of the blue so that the temperature of the light reaching the film is 3,400 degrees. Where it is too yellow, the filter will hold back enough of the yellow so that the temperature reaching the film is the same. It would be more nearly correct to say that the response of the colors in the scene would be the same as though light of 3400 degrees K. were falling upon it. Regardless of what the temperature of the encountered light, within the scope of these filters, properly used, they will hold back that color in just the right amount to give the effect of raising the temperature, or dropping it. to the standard figure which will give perfect color reproduction. The expedient by which this is accomplished is simplicity itself, once the amateur has had sufficient practice with the color temperature meter to assure himself that he is getting the correct readings. In this meter, there are two semi-circles which, when combined, form a complete circle. One semi-circle has a fixed color; the other one is variable, by means of a knob on the outside of the instrument, which is attached to a pointer on a scale. Looking into the eyepiece, with the meter directed at the source of the light, this knob is rotated until the semi-circle with the variable tone matches the semi-circle with the fixed tone. At this point a reading is taken, directly in degrees Kelvin — the color temperature of the light measured. When the readings obtained show 3,400 degrees the j-cene can be photographed without any compensation. If the readings obtained are below this figure, then the compensation filter will be one of the blue shades. Picking out the lightest, this filter is placed directly in front of the aperture admitting the source light, and the knob rotated in the usual fashion until a match is obtained in the semi-circles. Again the reading is taken. It will be found that this reading will have a higher value. If, however, it does not reach the 3,400 mark, the next deeper shade is measured, and this process continued until the filter chosen brings the reading to exactly the equivalent of photoflood illumination. The filter found to give this correct reading is the filter used on the camera. Should the original readings without the filters go above 3,400 degrees, then one of the yellow filters will be necessary, and the procedure will be the same, except that the readings will become less and less until the point of photoflood equivalent is reached. In using this equipment a few points should be remembered. Every person has a somewhat different eye-response to color, so the meter must be corrected against a standard candle for each individual. Also, the match, in order to have any practical value, must be extremely accurate, and the eye is prone to tell us that they do match, when actually they are slightly off. For this reason, as in the case with all scientific instruments where the possibility of human error is present, it is necessary to take several— sometimes as many as ten — readings, and these readings averaged up. The problem of physical fatigue, and eye fatigue, is a considerable one, and must be reckoned with. Once these processes are mastered and the readings held to the optimum point, a consistency in fidelity of color reproduction will result. The problem then resolves itself into one of keeping the scene illuminated by sources whose individual color temperatures are the same. Generally this is fairly easy if the bulbs are of the same type, are of similar age, and are operating from the same line source. If a change of voltage has occurred it will be the same for all the lamps, and an overall correction at the camera with the filters will take care of the situation. Only unwanted daylight will then give a distorted rendition. Agfa Improved Indiatone Paper 9 The warm-toned Indiatone paper which has been widely employed for both projection and contact printing is now being supplied by Agfa Ansco in a new. improved type. In addition to being richer in tone and easier to handle than that previously supplied, the new Indiatone displays excellent stability and latitude characteristics and is marked by an improved gradation that exhibits softer highlight detail without sacrifice of shadow brilliance. New Wabash Bulletin # Camera fans who want the latest data on flash, flood and color photography may secure a copy of the new Wabash Exposure Bulletin, Form 732P, just off the press. This bulletin lists all popular films with complete exposure tables for their use in flash and flood photography with between-the-lens shutters, as .well as focal plane shutters from the minicamera size to the largest 4x5-inch Speed Graphic size. A special page idevoted to color photography with the latest exposure data tables available for both indoor and outdoor use with flash and flood. Readers of International Photographer may secure a copy from Wabash Photolamp Corp., Brooklyn, N. Y. Orr and Nan Wvnn in New Short • The first of "Warner Bros.' 1941-42 shorts schedule to go into production will be "Those Good Old Days," co-featuring William T. Orr and Nan Wynn. Jean INegulesco will direct the two-reeler.