Moving Picture World (Jul 1916)

636 THE MOVING PICTURE WORLD July 22, 1916 Ana mnmi»ii»niiw».— .^■uit|Miiinip^TfTTTnnnm'iiiiiiTiTiiiiiiiiiiiiiiiiiiiniiiniiir^T-JUiiiiiiiiiii|)||iii]iii lllllll^ w ^ AMAAi 1 Jm& KynBMBWBBWBIBB pJ!<A^AAAAAAAAAA>J''' Motion Picture Photography m> Conducted by CARL LOUIS GREGORY, F. R. P. S. Inquiries. QUESTIONS in cinematography addressed to this department will receive carbon copy in the department's reply by mail when four cents in stamps are inclosed. Special replies by mail on matters which cannot be replied to in this department, $1. Manufacturers' Notice. It is a rule of this department that no apparatus will be recommended editorially until the value of such appliances has been demonstrated to its editor. Black Finishes for Amateur Camera Builders. In response to several queries for means of finishing the metal parts of cameras, are given the following directions : For camera parts a dead black finish is requisite, a lustrous finish being the cause of reflections. Formulas for blackening various metals are quite simple, but their efficiency should be tested on odd scraps of metal before treating the camera parts. For Brasswork. Clean with fine emery and rinse ; immerse in a saturated solution of copper nitrate for about two minutes and then remove and heat over the flame of a Bunsen burner or other clean flame, such as that of an alcohol lamp. Repeat this process several times, until the desired depth of color is reached. A saturated solution of copper nitrate can be made by dissolving an ounce of copper filings in two ounces of nitric acid ; this should be done in open air, stirring the mixture as an aid to solution. Do not breathe the red fumes, which are highly poisonous. Another method of blackening much used by instrument makers on brass articles is : 10 per cent. Ammonia 25 parts Dry Copper Carbonate 5 parts Water 75 parts The cleaned brass is immersed in this solution with agitation for about fifteen minutes, or until a satisfactory black is obtained, when it is rinsed and dried or baked. The solution should be about blood heat. For Zinc Farts. Clean with emery and rinse off all grease and dirt, using hot water. Immerse in a solution made up of copper chloride 45 grains, zinc nitrate 30 grains, water 4 ounces, adding one-half ounce of hydrochloric acid, after immersion until the' right color has been secured, rinse dry. Tin Parts. Boil water, 1 ounce ; borax, 15 grains ; shellac, 30 grains ; glycerine. 15 minims. Boil until all dissolved and then add 60 grains of nigrosin. Immerse until desired color is reached. Bellows Interiors. Use a thin solution of shellac dissolved in alcohol in which lampblack is mixed to give the right color. Camera Woodwork, Interior. In 10 ounces of hot water dissolve Yi ounce shellac and 'A ounce borax. Then add y2 dram of glycerine and sufficient aniline black to make a deep black color. There are also many black lacquers on the market which may be used for the coarser metal parts, but they are not so permanent as the methods given. High Prices for Sugar. J. Rufus Wallingford has entered the Photographic arena. Blackie Dawes has ironed out his silk hat, re-waxed his mustache, put on his famous tan spats and is seeking whom he may devour. The shell game man has his lay-out spread on the table and the gold brick gent has packed his satchel with phoney money. The market price of sugar, just plain sugar such as you carelessly dumped into your coffee at breakfast this morning, has gone to twentyfive dollars a pound, salt is as precious as platinum and starch can no longer be used on your fine linen. You don't need to call the police to protect you. But you will probably go down to the surrogate's court and ask to have a guardian appointed if you buy some of the "substitute" developers on the market, and after finding that they don't work as well as they should, you send them to an analytical chemist for a report. The Eastman Kodak Research Laboratory has been doing some valuable work for you. Here is what was found in a "developer" that sells for over $30.00 per pound : Metol 10 per cent., Hydrochinon 16 per cent., Sodium Sulphite 30 per cent., cane sugar 33 per cent. Other constituents (mostly water) of no value as developer, 11 per cent. Figuring Metol at $50.00 per pound, you could make up this "developer" for less than $6.50 a pound. Sweeten to taste" seems to be the rule in the manufacture (!) of war-time developers. Three contain sugar in quantities varying from 30 per cent, to 50 per cent. But sugar is not the only table luxury introduced. Another contains 36 per cent, of table salt and some Pyro, while another contains 40 per cent, of the ordinary wash-tub variety •Copyright, 1916, by the Chalmers Publishing Co. of starch. The directions on the bottle do not state whether or not this starch acts as a mountant and does away with the necessity for the use of paste. Anyway it's better for the photographer to buy his paste separately from his developer. It's likely to save him from fifteen to twenty dollars a pound. The warning is : Make your own substitutes. If you want to use sugar, salt and starch in your developer, go to the grocer. He may charge you war prices, but not Wallingford prices. The manufacturers of papers and plates are keeping chemical prices as low as possible and are publishing revised formulas to help out the situation. Watch the direction sheets and make your own substitutes. How to Clean a Lens. The lens should always be kept clean from dust, grease marks, finger prints or other impurities. For ordinary cleaning in the field one should carry a tight envelope with several sheets of lens paper which is a very fine, satiny, soft Japanese tissue which may be purchased for a few cents at any optician's or good photo supply house. To give a lens a thorough cleaning spread upon a table a clean sheet of paper ; take the lens apart, and with a clean camel's hair brush dust each of the combinations on both sides. If the surfaces are very dirty and have lost their polish, make up the following: Nitric acid 3 drops Grain alcohol 1 ounce Distilled water 2 ounces Dip a tuft of filter cotton in this solution, rub each side of the lens, then polish with an absolutely clean chamois. As new chamois is often softened with oil it should first be thoroughly washed in soap and water and dried and well softened by crumpling and rubbing with clean hands before using. Never use old chamois unless absolutely sure of its perfect cleanliness, as the same property which renders it such a good cleansing agent also makes it liable to pick up bits of grit which may injure the delicate polish of the lens. A small cleanly defined scratch does not damage a lens perceptibly, nor do small air pubbles in the glass, as they are unavoidable in the present stage of development in the manufacture of optical glass, but many fine scratches or perceptible dimming of any of the polished surfaces are serious defects and the lens should be returned to the maker for repolishing, or if the defects are of any appreciable depth, the lens should be disposed of and a new one purchased. If, on placing one of the combinations on a piece of white paper, any discolorations can be observed, whether yellowish, spotted or prismatic sheen, it is probable that the balsam which cements the elements together has deteriorated and the lens should be sent to the maker for re-cementing. It is too delicate a job for any except an expert optician : for if the center of any of the elements is thrown out of alignment with the optical axis you have ruined all of the finer corrections of the lens : although you may not be able to detect it with your eye. Clean the lens tube before replacing the lenses, each of which should be finally dusted with a camel's hair brush. "American Photography Exposure Tables." There has just reached our desk a copy of the new edition, eightyfifth thousand, of the "American Photography Exposure Tables." This valuable booklet has been completely revised, and contains accurate tables for determining photographic exposures under all conditions in all latitudes throughout the world. It lists all plates now known to be on the American market, and contains, in addition to the tables, a concise and comprehensive treatise on photographic exposure, outdoors and indoors, by day and by night, for still and moving objects and for copying, reducing and enlarging. The book is completed by a number of pages designed for exposure records. Published by the American Photographic Publishing Company, Boston. Massachusetts. Price, vest pocket size, bound in cloth, twenty-five cents. While this valuable booklet is intended primarily for the still photographer, it is of as great value to the motion photographer, and especially those who go about recording the strange places of the earth. By applying the simple calculations necessary in the matters of diaphragm and shutter speeds these tables apply as well to the motion camera as to the still box. A List of Plate and Film Speeds. We have just received from G. L. Harvey, manufacturer of the Harvey Exposure Meter, 105 South Dearborn street, Chicago, a new list of carefully compiled plate and film speeds that should add very greatly to the usefulness of this popular meter. Mr. Harvey has also gotten out a little folder that goes very thoroughly into the matter of motion picture camera exposures and every motion picture photographer should send for a copy of this folder. With the information that it gives, even tyros in motion picture work should find no difficulty in the overcoming of that bugbear of correct exposure in making motion picture film.