International photographer (Jan-Dec 1941)

lamp does not require the special wiring necessary for ordinary studio lamps. 15. Reasonable portability. Reflectors and power units for three lamps can be carried in the rear end of a business coupe or sedan. Solves Long-Standing Problems With the Kodatron Speedlamp. ultraspeed photography is no longer a laboratory stunt. Subject motion, once a problem in many fields of photography, is now an asset. The new lamp also provides complete freedom from certain other limitations of the past, and greatly extends the range of practical photographic subjects, treatments or effects. For the commercial and illustrative studio, it solves the ancient three-horned dilemma of subject motion, field depth, and adequate illumination — especially in color photography. In the scientific, medical, and technical fields, its uses are virtually unlimited. It has definite application in portrait photography, whenever an apparently unposed, characteristic effect is desired, or when the subject is a child or unpredictable pet. Where large areas are to be covered, the Kodatron lamp has unusual value because of its long throw and great intensity. In spite of its apparent mildness, the single flash provides illumination equivalent to that of 50,000 forty-watt tungsten lamps. This quantity of light is sufficient to provide a fully-timed negative of an average subject 30 feet from the camera at a lens aperture of f/11, when used with films especially recommended for this type of radiation. Correspondingly smaller apertures can be used when the subject is nearer the lamp (or lamps). The Kodatron flash is accomplished by discharging a condenser through a gasfilled tube. Ordinary 115-volt, 60-cycle current is led into the power unit of the lamp, where a specially-constructed transformer steps it up to 2,000 volts. This current is then rectified and used to charge a condenser. When the trip circuit is closed ( manually, by a flash synchronizer, or by the photocell unit), the energy stored in the condenser is discharged through the tube, producing a flash of high photographic efficiency. In photography with the Kodatron lamp, the time of exposure is fixed not by the shutter speed used but by the duration of the flash. An effective flash duration of nearly 1/30,000 second combines high volume of light with ability to stop virtually any moving subject, except a rifle bullet. In these high speed lamps, the time of the flash is determined by the capacity of the main condenser in the power unit. By iisin^' a small condenser, it would be possible to speed up the flash to any desired point — such as 1/1,000,000 of a second, or less but the volume of light would dei -line correspondingly, thus reducing the general utility of the lighting unit. For this reason, and on the basis of extensive experiments, this flash speed has been selected as ideal for all-round usefulness. This flash speed is, of course, many times faster than the highest setting of any camera shutter. It is several hundred times as swift as the wink of an eye, and approximately ten times as fast as is necessary to stop an athlete in action. If one second were represented as a mile, the effective duration of the Kodatron flash would correspond to only a few inches of this distance. An interesting feature is that, owing to persistence of the image on the retina of the eye. the flash seems to last about 1/25 to 1/50 second; and when a swift-moving subject is photographed by means of these lamps, it will appear to "freeze" for just about that length of time. Current Consumption is Small With the Kodatron lamp, one flash can be made every ten seconds — this being the charging time of the condenser. The charging takes place automatically, and the tensecond period allows convenient time for changing film and resetting the camera shutter. Current consumption is quite small during the charging cycle — about five amperes at the start, decreasing in a few seconds to less than one ampere — and this explains the extreme operating economy of the Kodatron lamps. Two to three of the lamps can be operated safely on an ordinary house-lighting circuit fused for 15 amperes. Quality of the Kodatron light is excellent for photographic purposes, not only in actinic value but also in color balance. Excellent tonal rendering is obtained in black-and-white photographs on panchromatic films without the attendant over correction in the red, which is characteristic of these materials when used with tungsten illumination. For color photography, Professional Kodachrome Film yields highly satisfactory results when used with moderate correcting filters. The Kodatron Speedlamp is a compact, efficient studio unit. It consists of a power unit 8x10x9 inches, and an 18-inch spunaluminum reflector on a telescoping steel stand which can be extended to a height of eight feet — both mounted on a small traytop steel base to which rubber-tired, swiveled casters are attached. Finish is gray, with some metal parts finished in polished chrome. Portable for Assignments For assignments away from the studio, newspaper office, or other base of operations, the reflector and power unit alone may be used. Each power unit has a convenient carrying handle on top. Reflectors can be mounted on tripods, without need of alterations, or can be held by assistants. The weight of the power unit and reflector is about 40 pounds; that of the complete lamp with base, 59 pounds. Ordinary residence, hotel or convention hall wiring is adequate for these lamps, as noted above. Controls are concentrated in a small panel on top of the power unit. These controls include the flash trip, "off and on" switch for the main power line, and a red pilot light which shows when the unit is in operation. A single cable from the power unit to the reflector carries wiring for both the flash lamp and modeling light. The lamp cable, and the 115-volt, 60-cycle electric supply cord, plug into the sides of the power unit, and must be removed before the hinged top can be lifted. This arrangement — plus an automatic cut-out switch which functions as the power unit lid is opened — makes it impossible to touch a "live" connection. The flash lamp itself has a tubular frosted glass shell, fitting over a spiral glass tube which contains a mixture of rare gases. This is the flash element, the gas heating to incandescence when the condenser charge is released through it. Centered in the coil of the gas tube is the modeling light, a projection type bulb of moderate wattage and long life. Synchronization of the Speedlamp to the camera shutter action may be accomplished by the simplest type of contact adjustment . (A special synchronizing unit for use with shutters having a cable release socket is available. ) After attaching the synchronizer, the shutter is simply held up to the lamp, and the release operated. If the flash reveals the complete circular aperture of the lens, synchronization is perfect; if the shutter blades are seen partly opened, a slight further adjustment is necessary. This ease of checking makes it possible to test the synchronization at any time, without the bother or expense of test exposures. As many lamps as desired may be flashed in synchronism, to cover large areas or to obtain better modeling. Two methods are practical. One is to use wiring from lamp to lamp; the other, to use small accessory photoelectric trip units which clip directly to the lamp standard. Photocell Control is Convenient In photo-electric synchronization, a photocell unit is used on each lamp except one, which is connected by wire to the camera shutter. Inter-lamp wiring is eliminated, since the shutter-actuated flash of the first lamp fires all the others, through the action of the photocell units. This method of synchronizing is particularly convenient when the set-up is extensive, or when lamp-to-lamp wiring would be in the way. Outdoors, or in a dark-walled studio, the photocell units are effective at distances up to more than fifty feet, but in these locations each photocell must be placed so that it can "see" the first lamp. In a studio with light walls, the photocell units will operate by reflected light, almost regardless of their placing. They cannot, however, be accidentally actuated by daylight or the general studio illumination. 16