Home Movies (Jan-Dec 1940)

PAGE 296 HOME MOVIES FOR JUNE Photrix Cine A real movie exposure meter, madT'especially lor movie work The ,,,ov;;: ^ of his main camera setun That is why . . . his camera angle u n(), satisfac ordinary exposure m pHOTKIX lory for motion-p.etu^ ^nera owners Ihe* Of movie work. here ark its outstanding • ^°e adjusmiem^ecordin'fTlo^ Specific shut ^“fy°Urm#Vi;rr e^ lens ,No setting between shots-., opening directly. • SendJioilns oceurring^t^eiue photography. fined light acceptance a = The ideal camera, with SZZXS&J***. « Top-grain cowhide $22' zipper case, Sl.»« RANGES , . O 75 to 4500 cdl./9q. ft Brightness: O.:o Lens Opening: F:1 to F:32 ° Light Acceptance Angle: 50 0 75 to 800 W., 8 to Film Speed: 0.0 w 38 SCH. c • 6 fr./sec. to l*-o Operating Speed. 6 tr / fr./sec. 1 ot 16 fr./sec. adjust Shutter speed at 1 / able from 1/25 to 1/50 see. h more than 25 MADE IN U. S. fl. by craftsmen with i years experience in electrical precision instruments. Photrix Cinsturdy . . . built for years of faithful service. At your dealers, or write Dept. P-6 INTERCONTINENTAL MARKETING CORPORATION, 8 West 40th Street, New York 4 STAR + Titter • Top — Titler complete with supplemental lens holder and built-in wipe-off device. Below — Showing glass bracket in place, used in making superimposed titles. Price, $2.50. 75 *13 Lights, $4.50 Extra For Year 'Hound Filming Activity After the winter title-making season, use it for ultra-closeup filming of plants, flowers, insects and other nature studies! ★ ★ ★ ★ Adjustable camera base accommodates every make of 8mm, 9 Vimm, and 16mm camera. Alignment and centering of titles is simple and accurate. Title board is readily adjustable to either small typewritten or large 9"xl2" title cards. ★ ★ ★ ★ Will make praciically every wanted kind of standard movie title, including zoom titles_-wipe-off titles, etc. Additional accessories, available at small cost, make possible scroll, flopover, superimposed titles and oihers. HOLLYWOOD CINE PRODUCTS CO. 3221 South Figueroa Street Los Angeles, Calif. process of “hopping up” Kodachrome film, a few words of caution here may enhance results : In placing the film in the box or container with the mercury, make sure the mercury will not spill from its container and touch the film. Contact of the mercury with the film will fog it badly. Use the hyper-sensitized film as soon as possible after it has reached its speed peak — say four to six days after placed in the container with the mercury. And last but not least, rush the exposed film to the processing station as early as possible after it is removed from the camera. Decrease of film speed begins immediately after the hyper-sensitized film is removed from the mercury. EM a ^Jelephoto (e lens ® Continued, from Page 285 the camera. Aluminizing costs about 50c per diameter inch. This service is usually available from optical supply houses. Figure 2 shows how to find the reflected focal length, and the ratio or speed of it, after the aluminizing process has prepared the lens for use. A sharp miniature image of the sun or moon or a distant electric light forms on the white card when the concave reflector is held at a distance from the card, representing its exact focal length. The reflected focal length is always one-half of the radius of curvature of the concave surface. A li/2" concave mirror of 9" focal length would make an F. 6 telephoto of 9X power for 16mm use and 18X power with 8mm, compared with standard lenses. Do not try to make a telephoto any faster than F.5.6 to F.8 from spectacle lenses, as the curve must be very accurate in the larger ratios. A small flat mirror set at a 45° angle is needed, as shown in A, figure 1. This should be Vs" or Vi" thick polished plate and must be flat, not wavy, glass. Its width should be about twothirds of its length so that it appears about square when viewed from the opening that fits the camera lens. Its actual size depends on the size and ratio of the concave mirror. It should also be aluminized on its outer surface (one side only) so that no light passes through the glass but reflects direct from the concave mirror on the film. Two or three thin adjustable metal supports hold this secondary mirror (or prism) in place. The loss of light caused by the secondary and its supports is negligible. See layout in figure 3 for determining the width of the secondary. Naturally, the shorter the mirror ratio the larger the secondary must be to reflect all of the rays to the film. Be sure to make the shorter diameter at least as wide as the largest diameter of the film frame, whether it be 8mm or 16mm. Figure 3 shows how to mount the mirror cell and also an easy way to make it focusing. The cell can be turned on a lathe from hardwood or aluminum. The mirror must fit snugly but notrtight. Sheet cork or felt is good for this purpose. Everything — particularly the two mirrors — must be lined up true. The aperture can be stopped down by placing small neutral density filters in a slot located between the secondary mirror and the camera opening, as shown in figure 3. Small discs with circular openings could also be fitted in a slot in front of the main mirror. They cannot be made smaller than about F.8 or F. 11, however, unless the “Herschelian” principle is used. The finder shown in figure 3 is self explanatory. Its length is the focal length of the telephoto and it is fastened at some convenient place near the top of the telephoto. It is adjusted to include the same area as the mirror. This is found by observing the groundglass image at the film gate or making small tests on positive film and adjusting the angle of the finder until accurate. Natui’ally, a tripod or other steady support should always be used with