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The photographic news
- Bandzählung
- 29.1885
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- 1885
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- Hochschule für Grafik und Buchkunst Leipzig
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- Hochschule für Grafik und Buchkunst Leipzig
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- Bandzählung
- No. 1417, October 30, 1885
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Zeitschrift
The photographic news
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Band
Band 29.1885
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- Register Index III
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Band
Band 29.1885
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OcTOBER 30, 1885.J THE PHOTOGRAPHIC NEWS. 693 in the developer, being developed simultaneously. After the im27P8 had presented themselves fully, and were allowed to advance sufficiently far enough to admit of the amount of detail in the shadow expected from such being seen, Mr. Cooper made the addition of sixty grains of pyro, dissolved in two ounces of water, with 200 grains soda carbonate, when immediately the intensifying began, and the negatives rapidly increased in density. As soon as development was complete—which was judged after the negatives presented about one and a-half the strength of an unfixed dry plate—they were placed, after thorough rinsing, by Mr. Jones for half a minute in a solution composed of— Common alum 16 ounces Water 61 „ After which they were transferred, without further rinsing, to a bath consisting of— Hyposulphite of soda 8 ounces Water 32 „ . In all these operations the negatives were treated as nearly simultaneously as possible. The fixing was quickly accom plished, which was apparently the result of the solution acting on the negative on both sides. This fact holds good in the process of washing also, greatly facilitating that operation. Tollowing the development, the following questions were asked by the President, and answered by Mr. Cooper :— The PRESIDENT.—How do you varnish the paper negatives ? Mr. Cooper.—I do not consider it necessary to varnish them, except possibly in the case of portraiture, when it is desired to specially protect the retouching. The process of oiling renders the surface of the negative repellent to moisture, and is there fore quite as good a protector as varnish. The President.—Please explain the process of oiling. Mr. Cooper.—The negative being washed, and thoroughly dried either by squegeeing to the surface of an oiled glass, from which it will fall when perfectly dry, or by laying back down on clean paper, is ready for oiling. To oil, it is well to provide, first, a pad consisting of about six thicknesses of folded manilia paper. On this lay the negative, face down, and with a thick bunch of flannel or cotton-wool swab the back with castor-oil. using, say, a tea-spoonful for a 5 X 8 negative. Then with a flat iron, as hot as is generally used for laundry purposes, rapidly smooth it with an even pressure all over, following the path of the iron rapidly with the swab of cotton, which, being saturated with oil, fills rapidly the pores of the paper as soon as they are freed from the air in them by the heat. A negative, when properly oiled, should present an even dark surface, without any appearance of grain or mottle. It is only necessary after this operation to wipe the free oil from both the face and back of the negative, drying the face as carefully as you can, and then pro ceed to print in the ordinary manner by laying it on glass of suitable size and bringing the sensitive paper in even contact by pressure. No fears need be entertained of injury to the print from the presence of oil. In my experience so far, I have not seen a single print that was injured by the presence of oil. Although 1 have seen many that certainly had oil on them, which could only be seen by holding them up so as to transmit the light, it was quite impossible to see it on the surface. [Here some prints were shown to demonstrate this fact]. The President.—Can lantern transparencies be made from these negatives that will show no grain when projected on the screen ? Mr. Cooter.— My own experience is limited on this point, but I will state that of a gentleman who ordered a full outfit to make pictures in the Yosemite for lantern transparencies, a branch of the profession he devotes himself to exclusively. His decision in favour of paper was made only after he had practi cally satisfied himself of the possibility of making perfect slides from the paper negative. The President.—What is your reason for starting develop ment slowly, and finishing subsequently with stronger solu tions ? Mr. Cooper.—My reasons were three : First, because I was desirous of speaking on the development while at work, and wanted time to do so ; second, developing ten at once needed a dilute starter, so as to control them more readily ; third, very dilute developers have the tendency to make thin flat negatives full of detail, but weak. 1 obtain this result first, and then rapidly intensify by my addition of strong pyro. This gives me softness of detail, if wanted, or extreme density, if desired. The development of paper negatives should be continued until the image presents about from one and a half to twice the density of a glass plate. The President.—In the formulas you employ, do you use 437 or 480 grains to the ounce ? Mr. Cooper.—AU formulas for this work should be made up at 480 grains to the ounce, except in the case of the No. 2 solu tion, which is based on 437 grains to the ounce. The President.—How do you judge when a negative is pro pel ly fixed ? Mr. Cooper.—By looking through it as with a plate. The appearance is marked, and cannot be mistaken. Wherever the bromide of silver remains, an opaque appearance is pre sented. The President.—What light do you prefer for develop ment ? Mr. Cooper.—Either yellow post office paper, or green and yellow cathedral glass, if of safe tint and density. The following is his formula: — No. 1. Sulphite sodium crystals, pure (480 grs. to oz.)... 6 < 7, Distilled or boiled water ... ... ... ... 32 „ Pyrogallic acid ... ... ... ... ... 180 gip. No. 2. Carbonate soda, pure (437 grs. to oz.) 4 < z. Water ... ... 32 ., It will be noticed that there may be some drawbacks in the amateur getting the paper well oiled, as from the nature of castor oil it will dry out in spots occasionally. In addition to the demonstration, an improved Pan ell camera for instantaneous pictures was shown by Mr. Beach for 4 by 5 plates. The camera proper is enclosed in a neatly-covered black leather box. The rear of the camera is provided with a ground glass for focussing, which is attached to upright springs. The plate-holder is put in place by pulling the ground glass back, and slipping it down between the glass and the camera. The conical metal front portion of the camera slips over the tube of the lens, and at the joint is lined with billiard cloth to make it light-tight. To focus, a clamping screw is released, and the back of the camera is then quickly drawn in or out by the hand. A shutter rotates between the lenses, and is operated by a flat spring, the tension of which can be easily increased or decreased. Directly adjacent to and in front of the shutter, working verti- cally between the lenses and in the same plane, is a diaphragm disc, which rotates on its own axis similar to the discs in wide- angle lenses, enabling the operator to quickly bring any sized diaphragm into position, thereby dispensing with loose dia phragms, The arrangement permits the camera to be used for a time exposure with a small stop when desired. The releasing trigger is provided at its lower end with a direct attachment to the piston of a pneumatic cylinder, which latter is connected by a flexible rubber pipe to a coupling tube fixed in one side of the box. The rubber bulb and its tube is, by a very simple device, easily and quickly fastened to and removed from the coupling tube on the outside of the box. The trigger can, by this means, be operated by pneumatic power when the bulb is compressed in the usual way, or it can be independently worked by pressure on a spring button on the outside corner of the box. The shutter can be set for time exposures when desired, and quickly closed by pressure on the releasing trigger. The box has a dovetail metal plate secured to its bottom, which allows it to be fastened on to the metal head of a tripod by a sliding motion, thus dispensing with the usual tripod screw. The weight of the box loaded with oue double plate-holder was less than 4 1 lbs. A convenient handle and a neat nickle- plated spring lock gave it the appearance of a medicine case instead of a camera. In addition to a new compact 6) by 8} camera, con structed after his own design, George H. Ripley showed an improved Hoover shutter and diaphragm com bined, which attracted considerable attention on account of its novelty and the number of things it was capable of doing. The shutter was placed at right angles to the length of the lens-tube, midway between the two lenses. The working parts
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