Home Movies (1943)

HOME MOVIES FOR AUCUST • Movie amateurs are successfully filming closeups of flowers, insects, etc., without need of a supplemental lens or shims. Lens is merely unscrewed a halfturn or so in the lens seat to a point pre-determined and marked on lens barrel. Ultra-closeup^ Without Supplemental J{en£e£,. . By GEORGE 11 LOST camera lenses are capable of closer focusing rhan is generally believed. I discovered this sometime ago in seeking a simpler method of shooting ultra closeups without having to resort to an assortment of auxiliary lenses that provided a supplemental lens for each focal distance from 2 to 20 inches. ^'hile use of auxiliary lenses are quite satisfactory for filming titles where the same focal distance is used continuously, they are not satisfactory for such field work as filming in ultra-closeup of flowers, insects, etc. The very nature of the subject makes it necessary to be able to set exact focus in an instant and get the shot safely in the brief and often tare opportunity afforded to film it. If yours is a Keystone, Bell & Howell, Revere, Univex, Excel or Victor camera, it probably is equipped with a screw-base removable lens. By unscrewing such lenses slightly, the range of near focus can be materially increased. My experiments were made with a Keystone 8mm. camera fitted with an f 2.7 fixed focus lens. Having no facts or formulas to guide me, it became necessaryto make a series of tests in order to determine just how much the lens should be unscrewed to bring it into sharp focus on objects within the commonly defined "ultra-closeup" range, i. e., 2 to 10 inches. My object was to make a chart that would tell at a glance how much to unscrew the lens to focus SMITH camera on any point within the ultracloseup range. Once I had my chart, exact focus could be set by measuring distance of object from lens with a small ruler, than unscrewing lens the required amount for the distance. In order that my data would readily serve in those instances when an object was situated a certain distance plus a fraction of an inch away from camera, say 6'/4 inches, I decided to make a graph that would enable me to calculate lens adjustment for any distance between 4'/2 and 24 inches. The chart, pictured below, was the result, and was arrived at only after countless tests in which objects were filmed on a test strip at various points between the 4l/2 to 24 inch range. The means for determining how much the lens must be unscrewed are the little serrations or milled notches on the edge of the diaphragm ring of the lens, or where the shoulder of the lens mount meeting the camera is so marked, it may be used. If the diaphragm ring is used, diaphragm first must be opened the maximum or to the widest opening before counting of serration begins. With the serrations counted and marked off into groups of 5, 10 or 25, it is possible to set the lens in an instant, once distance from object to lens is known. Suppose object is 16 inches from lens. Reference to the chart shows that sharp focus can be set by unscrewing the lens the extent of 40 serrations. An object 5 inches distant would require unscrewing lens 152 serrations. The chart referred to, in this instance was that compiled for the f 2.7 Keystone camera lens and which carries a total of 140 serrations on the lens ring. The serrations vary in number on different lenses. A similar chart can be made for other • Continue J on Page 2ft incuts ma • Reproduction of graph charted by author for bis f/2.7 fixed focus Keystone camera lens. Graph shows how many serrations or "notches'' in lens ring lens must be unscrewed to bring it into sharp focus on ultra-closeup subjects at various distances from camera. \ ma *' -»" 4| » 120 f< )0 21 : 250