The international photographer (Jan-Dec 1934)

Fourteen The INTERNATIONAL PHOTOGRAPHER September, 1^34 TELEVISION INTERFERENCE By Harry R. Lubcke Director of Television, Don Lee Broadcasting System EVERYONE has heard static and interference over the radio, but few have seen these troublemakers on television. A discussion of their antics in the latter case is interesting. In the first place, static sounds worse than it looks. A crash of static makes itself known on the television screen as an instantaneous "snow" storm of small white flakes. The eye is more tolerant of the snowstorm, than is the ear of the crackles and crashes of which it is composed. The slight interruption is often pleasing, giving the looker a momentarv intermission, An ultra-high frequency receiver installation in a La Salle sedan, used to make signal strength measurements on the Don Lee ultrahigh frequency transmitter W6XAO. The antenna is the vertical rod on the rear of the car. This car was equipped with auto radio suppressors and is practically noiseless. which rests his eye for a brief second. Instead of being distracted by the intermission, the looker's natural curiosity to "see what he has missed" is likely to heighten his interest in the scene. Only when the crashes of static are repeated sufficiently often and with sufficient intensity to cause an almost continuous interruption, does their presence become objectionable. When this is the case, a sound program would be unintelligible. Should the looker be so unfortunately situated that a powerful local sound station would "ride over" into the television channel, the image takes on an "underwater appearance" with horizontal ripples. These may be pleasing if they are not too pronounced nor too long continued. The scene appears as though it were being viewed from a diving bell where gentle, but ever changing ripples play over the field of view. Both natural and man-made static is found on short wave television. On ultra-short wave television, it is largely absent, but is replaced, unfortunately, by automobile ignition interference. It is becoming more and more important that this needless source of interference be eliminated. There are several ways in which this can be done. One of the easiest is to equip the car with suppressors and condensers as are used in the usual auto radio installation. Ultra-short wave signals can be received in a suppressed auto with no more interference than is produced by an ordinary car 200 feet away, while if it is driven past the ordinary residence receiving location it produces no interference at all. An unsuppressed automobile gives considerable interference under the above conditions, and presents a problem which should be considered by every automobile owner and manufacturer. This problem will receive attention because auto mobile owners will soon become television lookers, and as such will not tolerate anything that will mar their own enjoyment. If the television receiver is located close to the transmitting station, clear images will be received in spite of interference. In the Don Lee television work, interference-free cathode-ray images have been received from the W6XAO ultra-high frequency transmitter at a location on West Seventh Street, one of the busiest streets in Los Angeles, on the ground floor of a building, and less than 50 feet from a constant stream of automobiles and street cars. On the other hand, in a residential district where one automobile per hour passes the house, each one is "seen and heard" for a distance of 200 feet on either side thereof, although the receiver is located in the second story and the house was set back from the street by 50 feet. In this instance the house was on a hill on the side away from the television transmitting station and therefore in an area of unusually low field strength, which required the receiver to be operated with the volume control full on. It is interesting to note the intensity of the interference created by the various makes of cars. All sound the same, giving a succession of sharp, intense clicks, but Model T Fords and certain other cars, not necessarily the large and heavy ones, give the most interference. It depends on the design of the ignition system, and whether or not the automobile is an old car, which may have become "weak" in its ignition, or "strong though weak" because of supplementary leaks and poor connections in the ignition system. It is, of course, desirable to reduce automotive interference by proper design at the factory, and certain manufacturers are conducting research in this direction at the present time. The public should encourage such activity by favoring such makes and thereby solve the automobile interference problem before it becomes acute. SINGLE-EXPOSURE LEICA CAMERA Many miniature camera enthusiasts often wish to make one exposure and develop it immediately. With the usual camera today this may not be so convenient. With this idea in mind, E. Leitz, Inc., offers the Oligo Single Exposure Leica camera. The Oligo is a most interesting little device. It consists of a metal housing, the front of which is threaded to accommodate any of the Leica lenses, and the rear is fitted to accommodate a special ground glass focusing screen and special film holders interchangeably. A special Ibsor shutter which fits over the lens and provides the exposure-speeds completes the outfit. The film holders are sturdily constructed of metal, and hold a single lxl V2 inch film which may be cut from a 35 mm. film roll. Sharp focus is established by the ground glass back. The Oligo camera is excellent for making test shots, for copy work, and for all other uses where but one exposure is necessary. See the Single Exposure Leica camera at your dealer's or write for additional information to E. Leitz, Inc., 60 East 10th Street, New York City. COERZ NEW BOOKLET The C. P. Goerz American Optical Company has issued a charming little booklet, entitled "Goerz Lenses for Photographic Accuracy," which will be read with interest by all users of photographic lenses. This little book is a silent salesman for the fine old house of Goerz and it will be mailed to all who send for it at C. P. Goerz American Optical Company, 317 E. 34th Street, New York City. Goerz lenses may be obtained through all dealers in photographic supplies and a free trial of any stock size may be arranged for through these dealers. Please mention The International Photographer when corresponding with advertisers.