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THE FOUR WAYS OF FOCUSING
F. S. Lincoln
A fixed focus lens could be used here
Photographs below by R. I. Nesmith
FREDERICK G. BEACH, ACL
PROPER focusing is not a troublesome problem in amateur movie making, for it is a simple matter to adjust the lens for distance correctly, and there are several aids in accomplishing this result. Lenses for 16mm. cameras have considerable depth of field at the smaller diaphragm openings, and, compared to the average still camera, with its lens of a focal length of approximately five inches, a movie camera, with its standard inch or half inch lens, presents relatively a very simple problem in focusing.
But, although focusing may be simple, it is exceedingly important, because a picture that is not sharp on the screen loses most of its beauty and interest. Therefore, a good movie maker is very conscious of focusing and the quality of sharpness of the image on the screen.
Using fape measure for closeup focus
A distance meter is valuable in a case like this
Visual focusing by viewing portion of lens field
Visual focus, giving full field without parallax
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There are four principal methods by which focusing is accomplished on amateur movie cameras. These four methods, illustrated on this page, are: (1) by means of a fixed focus lens; (2) by measuring the distance by tape; (3) by using a range finder; (4) by visual observation of the image through a device incorporated in the camera.
When the lens is of fixed focus, the problem of focusing is encountered only in making closeups, for everything from about five feet to infinity will be satisfactorily sharp on the screen when a scene is filmed with a fixed, or universal, focus lens. Such objectives are designed and built so that they will cover this field with even sharpness. Most fixed focus lenses are made with a focal length of less than one inch, 20mm. being the most common focal length in such lenses for 16mm. cameras and 121/2mm f°r 8mm. equipment.
It is only when the camera approaches within five feet of the subject that the user must concern himself with the question of focus. Then the answer to his