Movie Makers (Jan-Dec 1949)

62 ^kould ICod/AO^ ke "YES!" claims a reader, citing his experience WILLIAM H. KROUSE, ACL WINSLOW RANDALLS article. Tourist Tips on Mexico I October. 1948 I . was both interesting and enlightening. However, near the end of his discussion he says. "Remember, though, no color exposure smaller than / 11. no matter what your meter says." No doubt he is las are many other movie makers) a blind follower of the following statement which appears in a manual (page 17. Kodachrome and Kodacolor Films, 4th ed. 1948 — Ed. I published by the Eastman Kodak Company : Meter readings on outdoor subjects in full sunlight that indicate lens openings smaller than f/H for an amateur motion picture camera, or exposures of less than 1/50 of a second at f/8 with a 35mm. or Bantam still camera, should be disregarded, because underexposure is almost certain to result." STATEMENT QUESTIONED 1, too. followed that advice at one time (much to my sorrow I and the result was a lot of overexposed, washedout looking film. Finally, after losing a great many feet of film due to overexposure by following the above statement. I decided there must be other factors which determine the size of the diaphragm opening. Later, I had the opportunity of talking with one of Eastman's top color men. and 1 challenged their statement as being misleading. He was surprised that the statement appeared in that form in their manual and replied that that was not what was meant. He said, further, that he would discuss the statement with the company and have it changed; but I notice in the last edition, the one cited above, that no changes have been made. FACTORS INVOLVED When using black and white film no such advice is given. There, if the meter reading calls for a stop of f/16 or / 22. it is used and the results certainly justify such use. However, in the case of color film, there are several factors to be considered that limit the size of the diaphragm opening: 1. Color film is much thicker than black and white film. This is due to its three layers of emulsion, each separated by a layer of gelatin, whereas the black and white film has but one layer of emulsion. 2. Iif-L'ar r l]( — of advances in optics, there are still many movie ]iti-c in use which are not color corrected or which are of such inferior quality (due to cheapness of production i that they cannot be fully color corrected. Thus, each color floes not focus at the same plane. This is the reason wh\ box cameras often produce very sharp black and white negatives but yield unsatisfactory results when color film is used. 3. The diaphragm of a movie lens, especially that of the Vo inch on 8mm. cameras, approaches a pin hole in size when slopped down smaller than //ll. It thus utilizes practically none of the color correction ability available with the use of a larger diaphragm opening. EFFECT OF SMALL OPENINGS There is no doubt that, in most instances, if the meter reading calls for stops of f/16 or //22 or smaller, the results will be unsharp, not underexposed. As I have said before, this phenomenon is much more noticeable on 8mm. than on 16mm. color film. Therefore, the reason for not stopping down below //ll is not one of underexposure, but one of degraded definition. OTHER CONTROLS What, then, should be done in order to secure the correct exposure and yet not stop down smaller than //ll? There are several possibilities. A polaroid filter can be used, reducing the effective exposure by approximately two full stops. If the scene contains little or no movement, a shutter speed of 32 frames per second (equal to one stop less exposure) or 64 frames (two stops less exposure) can be used. For those having a Cine-Kodak Special, the variable shutter adjustment can be used to cut down the amount of light reaching the film without decreasing the aperture. In other words, one-half open is equal to one stop smaller and one-quarter open equal to two stops smaller. I have exposed color film over most of the United States, in Mexico, Canada and Alaska, and I have frequently had Weston meter readings of 800 foot candles or more — especially at the Valley of 10,000 Smokes in Alaska and at White Sands National Monument in New Mexico. Had I {and I have) used an opening no smaller than //ll at 16 frames per second, the film would have been perfectly clear, so overexposed that not even a trace of an image could be seen. It is my hope that those who read these comments will be saved the loss of never-to-be-replaced scenes so often caused by the misinformation prevalent in this //ll rule. In other words, if the meter calls for an opening smaller than //ll, and if you have no way (other than reduced diaphragm) to cut down on the amount of effective light — don't waste your film! If you do use a smaller // stop, you can be fairly sure of unsharp results. But at least you will not have underexposed film.