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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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- Bandzählung
- No. 1425, December 24, 1885
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The photographic news
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Band
Band 29.1885
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- Register Index III
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r 822 THE PHOTOGRAPHIC NEWS. [DECENBER 24, 1885. this point until he has developed and lost several plates. To his mind the details might be out with the shadows all white, or the entire plate might be dark brown, and the film one mass of fog. Either case could consistently occur, and he not be the wiser whether they were right or not. Therefore, it seems to me the study of the appearance of the image during development is of special importance to beginners, and more specific details re garding it should be put in our guide books. Experience is conceded to be the best book. At the same time it is possible to give certain prominent hints, which are sure to be useful to anyone. Having been accustomed to develop, some years ago, under a liberal quantity of yellow daylight, when using the wet process, and then experiencing no trouble whatever in quickly flashing out the image under the old iron developer, 1 was naturally cautious when I was told that the new gelatine plate would fog under that brilliant light, and that the development must be carefully watched, and certain strict injunctions about admitting white light through crevices of doors, &c., be heeded. Sol obtained some of Carbutt’s ruby paper and covered it very care fully over my yellow window. I was then working under a great abundance of diffused red light, which, according to some of the latest experiments, must have been quite non-actinic, coming, as it did, through yellow-red combined. To take the exposed plate out from the holder, lay it in the tray (for I had always developed the wet plate by holding it at one corner with my hand), and pour on the prepared developer of iron and oxalate, seemed novel to me at that time. I soon found patience was a prime necessity, and after waiting for five minutes the image commenced to appear. I imagined the ex posure had been too short—that I had overrated the supposed extraordinary speed of the plate—hence I added more iron. But when I had the plate well developed, the question arose, “ How am I to tell as to its density ? ” The ordinary advice is t > hold it up to a lamp and look through it, but I was using ruby daylight, and had no need of it, and I found it impossible to look through the plate ; hence I was all at sea as to density, and only judged from the surface opaqueness of the blacks, or what is commonly termed high-lights, that it would be right after fixing. And here comes another uncertain element in gelatine plates: if the development has been too short, the plate will fix out too thin, and the supposed intensity will disappear. How must we develop to know when the plate will fix out right? One person will tell you, continue the development until you can see a greater portion of the image on the back of the film, when you look at it by reflected light on the glass side. I have found this a very good guide in many cases, even superior to looking through by transmitted artificial light, for you are certain then that every portion of the film that has been aflected by the actinic light has been acted upon by the deve loper, and will remain after the plate comes out of the fixing bath. You ask: “ When this condition is reached, what is the sur face appearance of the film ? ” In a majority of cases, if pyro is used as a developer—which is what 1 advise—the film will have a slaty-brown colour all over, not quite as dark in the deep shadows as in the other portion, but it will be perceptible to the eye. Furthermore, the unexposed edges of the plates behind the rabbet of the holder will perhaps be a very light brown. Much depends upon the length of development as to this, and the quality of the plate. Ordinarily the edges should remain white throughout development, but when they do slightly turn, you need not fear but what you will turn out a handsome, clear nega tive. Another will say : “You cannot judge this plate by looking at the back.” When the whole surface of the film is well brought out, development should cease, though it appears all white on the back. I have had plates of which this statement was true, and have found them more difficult to judge by re flected light, regarding their density, than any other. Viewing by transmitted artificial light is here a necessity, and is the only way to tell when the development has been carried far enough. By holding the negative up to a certain standard oil or gas lamp, distant about three inches, for a moment, the eye can quickly judge whether there is any solid detail in the shadows, or sufficient opaqueness in the high-lights. And for anyone using a brand of thickly-coated plates, where profuse ruby daylight is preferrel during development, I would advise the employment of a lamp which could be kept burning low, and turned up only as you wished to examine the state of the nega tive. By this means you can familiarize yourself with the appear ance of the plate in the different stages of development, and soon learn when to stop. One manufacturer has told me to continue the development, in using his plates, until the white rabbet edges of the plate commenced to turn slightly, reasoning that all the detail that it was possible to bring out was out at that stage, regardless of the appearance of the back of the film. I found this a good guide, but by continuing the development further, though the surface appeared quite dark, I obtained a negative more dense, and just as clear. It takes some experience to tell by the ruby light, as it is reflected upon the negative in the developing tray, whether the details fully appear on the surface, for the reason that the light itself is so poor in illuminating power. Consequently, be ginners are often deceived. The moment the prominent objects appear to be fully out, the plate is at once removed, and, after fixing, the operator is dis appointed at finding so much that is missing. My experience is that it is better to have the image appear at least one-third darker by the ruby light than you think it ought to, in order to secure a good negative afterwards. Sometimes we are deceived by the appa rent turning of the rabbet lines on the edges, which is really due to the reflection of the red light from the sensitive film, and to the red colour of the developer. In the development of paper negatives, it seems to be much easier to tell by the surface appearance when it is time to stop, for we have a white back ground, as it were, similar to the effect of a ground or opal glass behind a transparency, which tends to bring out more the deli cate details in the shadows, causing them to be more easily seen than with the ordinary plate. Furthermore, the coating of the sensitive film on the paper is thinner than that usually put on the glass, and as the developer acts upon both sides of the film at once, through the paper on one side and direct on the other, a considerable portion of the prominent details of the picture can be seen by looking upon the back of the paper by reflected light when the development is completed. The developer also acts very evenly upon the paper. There is no danger of air bells or frilling, and it is remarkable with what ease and safety from four to half a dozen or more negatives can be developed in one tray, with one developer at a time. Supposing from ten to fifteen instantaneous exposures have been made in one day, and it is desired to develop them rapidly. Cut off half a-dozen sheets at a time, and immerse them one by one over each other in a pan of water ; then turn the film side up, drain off the water, and pour on the developer, weak in the alkali, increasing it by degrees until the development starts. You have the whole matter then under your control, and can examine each negative as leisurely as if you were toning, and you have plenty of time to manipulate the developer to obtain any effects you desire. It was not until I actually tried it, that I realized the pleasure and satisfaction to be obtained in develop ing these paper negatives. I made three successive exposures on the same object, using the smallest stop, giving exposures of five, ten, and twenty seconds, developing all in one developer in one tray. I com menced by using a small amount of alkali, and when the twenty second negative was finished, I added more alkali, and brought up the other two to good density. I was therefore surprised and delighted to notice the latitude allowable. Paper nega tives can be dried very easily, so as to leave as smooth a surface as glass, after the hypo has been eliminated, by first putting a drop of any kind of oil on the glass, and apparently rubbing it off clean with a piece of cloth or paper, then laying upon this prepared surface, face down, the negative, pressing out the air bells with the finger, or squeezeeing the back with a velvet rubber squeezes, leaving the negative to dry. In place of glass, hard rubber can be used without oil. Both sides of the glass or rubber can be utilized. When dry, the negative is seized at one corner with the fingers, and pulled or peeled off the glass. It presents a beautiful polished surface, which will remain until the paper is either oiled or mounted. I have one or two specimens to show you. I have recently experimented further with developing by two solutions. I put two plates in a solution of pyro, four grains to the ounce, for three minutes, then poured it back into the graduate, putting on the alkali. When the development was complete, the plate was too thin in the high-lights, so I poured off the alkali, washed the plates with water, and put on the original pyro solution, strengthened up to about eight grains to the ounce. I simply let the pletes soak in this pyro solution
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