International photographer (Jan-Dec 1941)

l6MM. dcpARTMEINT What Shouldn't I Do? — III Perhaps our article this month could have more properly been titled A DISCUSSION ON FINDERS, but the fact still remains: DON'T TAKE YOUR FINDERS FOR GRANTED. So basically simple in its concept, yet a source of trouble to many because it is so simple, and often totally ignored because it has no direct mechanical connection with the actual process of the exposure of the film. We have seen pictures that were perfect from every technical standpoint, beautifully lighted, and interesting in their content, yet completely ruined because that seemingly unimportant little gadget, the finder, was not given its due consideration after all the "important" problems had been met and solved. Pictures that result from this sort of an attitude can be compared to the appearance a man will present who is most immaculate and impeccable in his dress, has bought the best in clothes, is careful about the color match of the entire ensemble, and has spent the necessary amount of time in their arrangement; but because a necktie is an accessory serving no specific purpose will grab any old piece of cloth that can be properly identified by that name, tie the thing in six seconds flat, and breeze out of the place with the rear length seven inches longer than the front, and with the knot two inches below the collar, and over to one side at that. Otherwise he is very well dressed! Specifically, an uncorrected finder will result in pictures that are too far over to one side — when the scene was viewed directly in the center while being photographed— or with the desired center too high on the screen, if the finder is not in the same horizontal plane with the lens; or we may find ourselves with a picture taking in much more — or much less — than we "thought" we were getting, depending upon the individual finder and camera, and how the camera happened to have been set before the "mistake" was made. To begin with, every lens used must have a finder or finder adjustment that is matched to it, and to it alone. Every lens of definite focal length has a definite angle of view, which in turn determines the exact area that will be included in a scene a given distance from the camera. To be of any value, a finder must have some means of varying its angle of view so that it will correspond exactly to that of the lens. This can be accomplished by any one of several different ways, or by a combination of two. In its simplest form, the finder will consist of a concave lens, used as an objective, ground to have an angle of accept ance to correspond with that of the widest angle lens used, and an eyepiece that is merely a "peephole" so aligned and spaced from the objective as to insure the correct distance of the eye to the objective to give the correct angle of acceptance. Finders of this type generally have markings on the objective corresponding to "correct" fields for lenses of narrower angles I longer focal lengths ) . Another type of finder, such as is used on the Bell and Howell 16 mm. cameras utilizes lenses for both the objectives and eyepieces, with a series of mattes of varying sizes built into the assembly. These mattes will shut out all but the actual angle included by the lens for which it is designed. Still another type is one having a convex objective lens focusing an image onto a ground glass, and the image thus formed being the picture corresponding to the image in the camera. Mattes, calibrated to include only the area taken in by the photographic lens, are used in front of the ground glass. While this is by far the most satisfactory, being used on the professional cameras, it is the least used in the amateur field, due to the cost, and the fact that it cannot easilv be incorporated as an integral part of the whole camera. Because of the impracticality of the latter— for general amateur use — we find the field limited to the use of the former two. The greatest shortcoming of the first type — the one using the objective with the markings and the "peephole" eyepiece — is to be found in the difficulty of placing the desired action within the confines of the correct markings without confusion; more often than not the action or scene, especially under stress of time, is placed in the wrong area; frequently they are merely used as "guides"! Any slight discrepancy in the alignment of these units will result in grave error of placement. Serious composition becomes a difficult problem because of the resulting confusion, and there is a tendency toward vagueness. Innate in all finders is the problem of PARALLAX, and before any serious work is contemplated this must be met and solved, especially for close-up work, as the closer the camera is working to the subject, the greater the problem. Parallax can best be explained as the inability of two lenses — working side by side — to take in the same identical view by virtue of the fact that because one lens is to one side of another it will show a view that is a little to one side of the view of the lens under consideration. AND BEFORE BOTH OF THESE LENSES CAN TAKE IN THE SAME IDENTICAL VIEW ONE OF THEM WILL HAVE TO BE TURNED SLICHTLY TOWARD THE OBJECT WHICH THE OTHER IS FACINC. This, simply, is the basis for the correction of parallax. Speaking specifically, if the lens under consideration is the photographic lens of the camera, then the lens of the finder is the one which will have to be turned so as to be pointing to exactly the same area which the camera lens is focused upon. It is obvious that the closer the object is to the camera, the greater will be the discrepancy, and the greater will be the necessary correction — or turning — of the finder to be pointing to the image focused upon the film in the camera. It is the failure to understand this point that is responsible for the many pictures, closeups especially, that result with the object either to one side of the screen, or with the top of the head cut off, depending upon whether the finder is beside the lens or above the lens. In professional cameras, extensive provisions have been made for the correction of parallax, a system having been devised whereby the adjustment is made automatically as the lens is set for any given distance; correction is also introduced for different lenses of varying focal lengths. However, to the best of our knowledge, the serious shortcoming of a finder being built into the camera with no adjustable compensation is a common practice in the manufacture of amateur motion picture cameras. And at the present time about the only thing one can do with this problem is to make tests to determine just how much the finder must be corrected for any given distance, and then compensate for this when shooting. If the finder is to one side of the lens, then compensation is effected by turning the camera to the left by the amount found necessary by experiment; if it is above the lens, then the camera must be tilted up by the predetermined amount. If it is possible to place a ground glass in the photographic aperture I a thin piece of ordinary tissue will do) and the image viewed in this manner, the camera can be placed on a tripod and the scene or object viewed through the finder, noting the necessary correction required in the finder to bring the image in its proper and desired position on the screen. It is important to remember that the required compensation will VARY with the distance of the object from the lens of the camera. The ideal solution to the finder problem, of course, is to employ one adjustable for parallax, but until the time comes when provisions have been made for them on amateur movie cameras, it will be necessary for us to give our present finders the attention outlined, if we will have our well dressed man appearing with his necktie carefully chosen, meticulously tied, and in place. 20