American cinematographer (Jan-Dec 1952)

repetitious. Change it in every conceiv¬ able way. Another factor important to develop¬ ing interesting continuity is varying the focal distances of scenes and changing camera angles. Nothing can be quite so boring as a repetition of all medium shots or all long shots — with no vari¬ ation. Knowing when to emphasize a sequence by moving in for a closeup or by shooting the scene from a different, perhaps more interesting, camera angle is the technique of the successful cine¬ matographer. When you have photographed your film according to a carefully prepared the camera lens. Similarly it was easy to design a finder with a lens which, like the camera lens, could be focused. But to interlock these with the actual focusing of the camera lens was a diffi¬ cult problem — especially since it was desired to make the finder equally ac¬ curate for lenses of all the many focal lengths commonly used. The answer was found in the use of precision-made cams. Since, with the exception of the somewhat infrequent use of wide-angle 24mm lenses, when a supplementary objective was used to widen the finder’s angular view of field, the same lens was at all times used in the finder, it was not difficult to inter¬ lock the focusing of the finder lens with the parallax-correcting pivoting of the finder itself. Interlocking these move¬ ments with the focusing of the photo¬ graphing lens was achieved by the use of a simple cam-and-roller linkage. Thus, with these improvements, it was now possible for the camera oper¬ ator to keep his camera lens in sharp focus throughout a dolly or zoom shot, merely by watching the scene in the camera finder and turning the focusing control as required to keep the image sharp. The action of the finder was governed by the use of interchangeable cams, each ground to the precise curvature which matched the characteristics of a given lens. The cams were matched, not merely to the general characteristics of all lenses of a given focal length, but to the precise characteristics of each indi¬ vidual lens. Lens and finder cam formed a fixed combination in any camera’s accessory equipment. A further refinement was the fact the focusing threads on the mounts of lenses of different foci were cut to differing pitches, according to the characteristics of the lens. Thus, over the range of set¬ tings between infinity and two feet, a 24mm lens required less than a half plan, you should have an interesting motion picture. It will reveal the thought and preparation put into it; and it will hang together without arti¬ ficial bracing. Some readers may say this is too much bother and work. But rememebr, all professional motion pictures are photographed only after they have been planned and plotted in a shooting script. No, it isn’t any bother at all. You’ll find pre-planning a great deal of fun. And it’s likely that it will result in giving you a renewed interest in your movie making — may be just what you need if you’ve been letting the dust gather on your camera lately. END revolution of the controlling handle, while over the same range, a 4I/2” lens required over a full revolution of the handle. The scales for all commonly used lenses were permanently engraved on a single focusing dial, and a movable indi¬ cator on the controlling handle obscurred all but the calibrations for the lens being used. The Technicolor Corporation, in de¬ signing its three-color camera, reached a novel, et very practical solution to the problem of follow focus. Because three films run simultaneously through the camera, it is not as quiet as cam¬ eras of conventional design. The sound¬ proofing blimp designed for the Techni¬ color camera therefore had to be ex¬ tremely efficient. One of the prime speci¬ fications for the blimp was that there be absolutely no metallic contact be¬ tween the camera and the blimp. This meant that conventional focus-control mechanisms, which all involve some form of direct contact between the ex¬ ternal control and the camera, could not be used. None-the-less, the nature of color cinematography called for an un¬ usual precise control of focusing. The solution reached by Technicolor engineers was simple: if mechanical linkage was ruled out, an entire elec¬ trical remote control was the alternative. The result is that Technicolor cameras are focused electrically, by a control which may be operated at the blimp itself or from a point several yards distant. (Fig. 2.) The control is operated by a pair of tiny Selsyn interlock motors. One of these drives the operating control; the other operates the focusing of the lens. Both motors operate from the same electrical current. When the two motors are excited by the same current supply, they automatically synchronize. When the shaft of one motor moves, that of the other at once moves in the same direction and to the same degree. The remote focusing dial is about 5" in diameter, and fitted with a fixed pointer running in a spiral track. Move¬ ment of the dial is controlled by a small crank, which is geared to the shaft of the Selsyn motor. Movement of the crank for any focal adjustment is about double that ordinarily involved in con¬ ventional mechanisms — a feature which simplifies minute focus changes. With the growth of 16mm industrial film production and the application to the photography of such films of all the modern techniques employed in feature films, it followed that there developed a need for a simple, efficient means of follow-focus for these cameras, too. About three years ago, Richardson Cam¬ era Company, of Hollywood, developed a highly practical follow-focus mechan¬ ism for professional 16mm cameras. The attachment, pictured in Fig. 1 and which is adaptable to any multiple lens turreted 16mm camera, involves a unique synchronized gear system coupled to a parallax-corrected view¬ finder, and actuated by a single control. As each lens is shifted into place, a cam automatically corrects finder for parallax. Footage dial on the extended focusing knob is visible to the operator behind the camera. This knob and dial assembly is detachable and may be set up and operated from either side of the camera. Another important feature permits all normal rack-over operations to be carried out without disengaging or re¬ moving the linkage with the follow-focus attachment. Perhaps the most interesting develop¬ ment in this field is the external followfocus mechanism which is a feature of the new blimp for the Eclair Camerette, designed and manufactured by the Benj¬ amin Berg Agency, Hollywood. (Fig. T) Follow-focus with the Camerette is greatly simplified through use of the camera’s salient feature — a finder which permits viewing the scene or image through the taking lens as it is being photographed. Thus it was compara¬ tively easy for Berg to design his blimp around this camera, and provide the ex¬ ternal control which merely rotates the focusing rings of the camera’s various lenses. Having no side viewfinder to contend with, the usual parallax-cor¬ recting linkage between finder and cam¬ era lenses is dispensed with. Incidentally, it is also possible for the amateur movie maker to gain the advantage of follow-focus for his dolly shots, too. Perhaps one of the simplest methods worked out by one amateur provided for a scale plate to be attached to the left side of the camera, with a graduated footage scale facing the FOLLOW-FOCUS IN CINEMATOGRAPHY ( Continued from Page 523) 552 American Cinematographer December, 1952