Journal of the Society of Motion Picture and Television Engineers (1950-1954)

the time factor of threading and setting the loops. For instance, a series of cameras has been developed in which a large part of the camera mechanism — the pulldown claws, the aperture and the film gate — is incorporated in the magazine or film box. This method, however, results in an overly expensive magazine of which there must be several for each camera. Also, the fitting of these magazines to the camera requires a high order of precision which cannot be retained during the normal life of the camera due to wear and tear incident to service use. Other cameras developed were limited to magazines with a film capacity of 50 to 100 ft with the necessary loops and sprockets incorporated within the magazine. However, this system was accompanied by troubles arising from installation of the necessary couplings and drives within the main body of the camera. Another system utilized feed sprockets incorporated within the magazines, but the accumulation of dust and dirt that could not be removed without completely dismantling the assembly was a source of trouble. In general, these camera types left a great deal to be desired in reliability, simplicity and ease of operation and maintenance. In summation, the problem was reduced to the following : 1 . To design and develop an automatic threading camera wherein the film will be threaded during the process of attaching the magazine to the camera. This also included the requirement that loaded magazines could be removed from the camera at a moment's notice and then re-used in the camera at any time thereafter; and 2. To divorce all moving mechanisms (except the feed and reroll spindles) and their accompanying drives from the film box or magazine. The Experimental Model 16mm Camera In the process of developing a camera that would comply with the aforementioned performance requirements, a 16mm experimental model camera was designed, built and tested (Fig. 1). The camera weighs 1 5 Ib and has been used as the vehicle to prove the feasibility and practicability of the numerous features that it incorporates. As indicated by the title of this paper, the major feature permits automatic threading of the camera regardless of the film capacity of the magazine. Other features include unique magazine light-traps, high-speed film pulldown movement for television and radar scope recording, a special stabilized shutter to minimize "shutter bar," constant-speed main drive shaft to insure smoother camera operation, turret locking ring as an antivibration measure, quickly removable electrical assemblies, and special features to facilitate television and radar scope recording. By selecting certain features of the experimental camera, it will be possible to develop special-purpose cameras including: (1) a combat version, also suitable as an amateur camera ; (2) a radar and/ or television recording camera that is portable and suitable for use in aircraft; and (3) professional versions, both 16mm and 35mm with reverse take-up and other refinements. In designing the camera, precision workmanship has been used where necessary. However, precisely fitting parts have been avoided where not required, as experience has shown that unnecessarily snug fits are detrimental — especially under extreme high and low-temperature conditions and also in the presence of fine particles of dust or sand. In addition, all precisely related parts, wherever possible, have been constructed as integral units. Provision has been made to permit simple adjustments of moving parts that are subject to normal wear. Magazine The principal feature of the camera is automatic threading regardless of the film capacity of the magazine. During the act of attaching the loaded magazine to Badgley and Fraser: Automatic Threading Camera 51