International photographer (Jan-Dec 1934)

/ iveni v-two The INTERNATIONAL PHOTOGRAPHER April,1934 Miniature Camera Photography \XPOSURE and Fine Grain: Exposure is a HH prime factor in determining the resulting grain in the negative. It seems peculiar that of all the phases of photography which the amateur can choose to use as a measure of his experience, exposure is the one usually selected. Many photographers usually pride themselves upon their ability to guess correct exposures, and despite the fact that reducing and intensifying solutions have to be resorted to frequently, their faith in their exposure-guessing ability remains unshaken. One of the beauties of the miniature camera is its exact precision, and this typifies the manner in which Candid photo: Max Baer, Walter Huston and Jack Dempsey, at the premiere of "Dinner at Eight". Taken by )oe Meyer with a Leica camera and Hektor f:1.9 lens. it should be handled to produce gratifying results. It may be practical for a man using 5x7 inch plates to rely upon the latitude of the emulsion, and approximate at the correct exposure, subsequently resorting to reducing and intensifying solutions if necessary. Miniature camera photography, however, really is a graduate form of photography in which exactness is the code for success. The owner of the small camera cannot afford to adopt such slipshod methods. The exposure should be full, but over-exposure must be avoided. When an overexposed negative is developed the rate of development proceeds at a rapid pace. The individual particles of silver readily break through their gelatin coating to form clumps of silver. Density will be built up at a fast rate, and in the resulting negative will be quite high. It has been definitely proven, that if a print of constant density is made from negatives of increasing density, the graininess of the print increases as the density of the negatives increases. Under-exposure on the other hand, though favoring fine grain, produces unsatisfactory results. It is obvious that if the happy medium of correct exposure is to be attained the aid of some mechanical device must be solicited. This is a simple matter for there are many reliable exposure meters available. Before considering exposure meters let me mention By Augustus WOLFMAN Jt A> a relatively inexpensive little device which is quite accurate— the Burrough Wellcome Exposure Calculator. This contains a list of tables denoting by figures the actinic strength of daylight during the different months of the year, and the time of day. Another table uses figures to indicate the relative speed of the film being used. By turning a celluloid disc so that both figures are together, a series of exposures are seen together with the corresponding diaphragm openings. Provision is also made for special subjects, such as beach scenes, clouds, etc. In general, exposure may be divided into two types, extinction or optical meters, and electric meters. In the extinction type the basis upon which the correct exposure is determined is taken upon a figure or other character which is just barely visible in the instrument. Reliable meters of this type include the Drem Meter, the Leicascope, Bewi, Practos, Gracophot, Tele-Bewi, etc. The Gracophot and Tele-Bewi are also distance meters. In the Gracophot a knob is pulled up and the object is seen upon a ground glass. A knurled ring at the end of the meter is then turned until the object is in sharp focus. The correct distance is then read from a scale on the meter. The Tele-Bewi has a distance meter of the military type attached to the exposure meter. Electric meters such as the Weston and Electrophot incorporate photoelectric cells which convert the light energy striking them into electricity, which in turn operates the needle of the dial denoting the strength of the light. The Bell & Howell Photometer, also an electric meter, works on a different principle. This contains a small battery and bulb. A dial is turned until the brilliance of the lighted filament matches that of the subject. The correct exposure is then read from scales on the meter. The exposure to use varies according to the speed of the film employed, so that meters have a provision whereby the speed of the film will play a part in determining the correct exposure. Two systems are used to denote the speed of an emulsion, H. & D. numbers and Scheiner degrees. Most meters employ Scheiner degrees. It is difficult to compare these two speed figures for both are determined in a different manner. It is possible to have a number of emulsions which have the same H. & D. number, and still exhibit widely different Scheiner degrees, and vice versa. Another factor which is quite disappointing is the fact that there is no standard method of determining film speeds. H. & D. numbers determined by one manufacturer will be different from that obtained by another. The same holds true with Scheiner degrees. The results obtained in determining the speed of an emulsion is dependent upon such factors as the color of the exposing light, the manner in which the exposure Please mention The International Photographer when corresponding with advertisers.