The international photographer (Jan-Dec 1936)

January, 1936 T h I N T E R N A T I O N A L P H 0 T () G R A P H E R Nine By AUGUSTUS WOLFMAN the fact that a panchromatic film may be employed, such films are still greatly sensitive to blue, and without the use of a filter the sky will be rendered too light. Greens are also generally reproduced too dark. When a yellow filter is employed the blue of the sky will be held back, and the latter will reproduce in a definite tone. Greens will reproduce lighter, resulting in less contrast. Especially in brilliant sunshine, in which case strong contrasts are prone fully exposed negatives than the other. This may be quite true. We may have two f:3.5 lenses of different construction, and when both are used wide open the results obtained relative to exposure will not be the same. The entire matter concerns itself with the manner of determining the numbers denoting the speed value of a lens. It is obtained by dividing the diameter of the largest diaphragm opening into the focal length. Left: Spring Cleaning, photo by A. Wolfman. Center; taken with a Summar f:2 lens wide open, on DuPont Superior film. Right, Waterfront, by Karl A. Barleben, |r., F.R.P.S. to exist, the use of filters will do much to eliminate harsh results. Formula for Supersensitive Panchromatic Film: Many amateurs still seem to experience dire results with supersensitive panchromatic films in relation to grain. There are many instances where the illumination is relatively weak, despite the fact that a supersensitive film and a fast lens are employed, as in night photography. In such cases the use of a developer containing metol is advisable, to bring out the shadow detail, extreme fine grain being sacrificed for the proper shadow values. However, there may be cases where sufficient illumination is present, allowing the use of an extremely fine grain developing solution. The Sease No. 3 formula is excellent, but many photographers object to the doubling of exposure necessitated by this developer. An excellent fine grain formula for supersensitive panchromatic films has been reproduced in these pages some time ago, however, for the benefit of those who are not acquainted with it, we are listing this formula below. This formula requires only normal exposure. Formula for Supersensitive Pan Films: Paraphenylene-diamine 6 grams Glycin 6 grams Sodium sulphite (dry) 37.5 grams Water, to make 500 c.c. The formula is prepared by dissolving a portion of the sodium sulphite in about 250 c.c. hot water; the paraphenylene-diamine is dissolved, then the glycin and the remainder of the sulphite, and cold water added to make 500 c.c. The developing times are: 30 minutes at 65°F., and 25 minutes at 70°F. Lens Speeds: Often we have heard from photographers that they have worked with two different lenses, both of the same relative speed, and using the same shutter speed, the exposures on the film not being the same. One lens will produce more However, due to variances in design or construction of lenses some may actually transmit more light than others, despite the fact that their speeds are the same, as determined in the manner stated above. Usually the differences are so small that the latitude of the film will amply take care of them. Straightening Film: This is the time of the year when many of the films made during the past summer season are being printed. Usually the photographer keeps his negatives curled up in the original roll, and if they have been kept in a warm dry place the rolls of film will have curled up to a considerable extent, especially in the case of cine film. In many cases the curled film hampers the photographer in enlarging. This condition can be remedied by rolling the film in the opposite direction of the curl, placing a rubber band around it, and then putting the film in a warm place, such as near a radiator, for an hour or two. A Hint: By adding a small amount of sodium chloride (ordinary table salt) to a normal MO paper developer, prints with more brilliance and of a colder tone will be produced. TA&La.^iWo^<i In Sound Recording THE NEW PRINCIPLE MINOR QUARTZ OPTICAL UNIT becomes an integral part of your sound recorder— this unit is cemented into a steel block — it focuses a beam of light of great intensify and actinic value a distance away and on the film, which PROVIDES CLEARANCE and PREVENTS SCRATCHING of the sound track. The width of the beam of light measures from .0005" to .0008" as it strikes the moving film. This Quartz Optical Unit was used for the sound effects in the recent production of the "Tarzan" picture, filmed in Guatemala and referred to in the March issue of International Photographer. Send for details and specimen of sound track. C. C. MINOR 1835 Whitley Avenue Phone: GR. 4781 Hollywood Please mention The International Photographer when corresponding with advertisers.