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The photographic news
- Bandzählung
- 12.1868
- Erscheinungsdatum
- 1868
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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. 531, November 6, 1868
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Zeitschrift
The photographic news
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Band
Band 12.1868
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- Titelblatt Titelblatt I
- Kapitel Preface III
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- Register The Index To Volume XII 619
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Band 12.1868
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530 THE PHOTOGRAPHIC NEWS. [November 6, 1868. The facts, it must be admitted, at first glance, seem sin gular enough, nothing in the means being apparently ade quate to produce the end ; but we think we can offer an ex planation of the probable causes in operation which will account satisfactorily for the result. When an ordinary developer is applied to the exposed film, it will be observed that the high lights appear first, the half lights following, and so in regular succession, the least illuminated details being developed last. It will also be observed that in the process of development there is a natural tendency to aggre gation in the deposit of silver: wherever light has most acted, there silver will be most readily precipitated, and hence, in an under-exposed picture, the lights acquire great density before imperfectly illuminated details are brought out at all. It must be borne in mind that whilst the haloid salts of silver in the film—the iodide and bromide—form the initial image, appreciable thickness and printing power are obtained from the free nitrate on the film. If these facts are borne in mind, then, it will be seen that after the deve loper is applied a double action is in progress, the image formed by light on the bromo-iodide of silver is in course of development, and the free nitrate of silver present is in course of precipitation on that image, giving it a certain degree of appreciable density, the rapidity of the precipita tion of silver being in the ratio in which light has acted. If, then, the plate be kept still, the free nitrate of silver, being equally spread over the surface of the plate, is gradu ally precipitated, and the lesser lights, commonly called the detail, slowly but surely acquire sufficient density from the precipitation of the nitrate of silver immediately in contact to give them printing value ; and the higher lights, only securing the precipitation upon them of as much free nitrate as is in contact with them, do not acquire excess of density. The result is a negative in which detail rather than inten sity prevails. But if, on the other hand, the plate be kept moving, the tendency to aggregation is brought into active operation. The free nitrate solution being kept in motion over various parts of the plate, the lights, which are brought out first, having secured the precipitation upon themselves of the silver solution in immediate contact with them, find themselves in constant contact with a fresh supply, which in turn is precipitated upon the parts which in virtue of the greater action of light have the greater attraction for it. The lights thus go on rapidly aggregating the deposit of silver. In the meantime the minor lights, consisting of the detail in the shadows, suffer in two ways: first, they are robbed of the silver which should have helped to build them up ; and in the next place, the high lights quickly acquiring sufficient density, the development is stopped, of necessity, before the less illuminated portions have had time for full development. We think that on this view of the case it will be seen that it is perfectly natural that keeping the plate in motion should tend to give intensity to the lights, and keeping it still should tend to give full value to the less illuminated details. We have before pointed out that the use of a weak developer tends to the production of contrast, and the use of a strong developer to harmony, the tendency in both cases being due to causes similar to those we have just ex plained : a weak developer, acting slowly, permits of the aggregation of deposit, by the lights, whilst a strong developer, acting quickly, brings out the detail rapidly, and, at the same time, precipitates the full proportion of silver thereon. Our own observation has confirmed the view of the effect of manipulation which we have here set forth ; and we doubt not that it will be borne out by the observation of intelli gent photographers, especially where large plates are used, which of course afford the best illustration of the facts in volved. A knowledge of facts of this kind will not only frequently be found useful, but will go far to explain the production of discrepant results with the same materials by different operators. ECHOES OF THE MONTH. BY AN OLD PHOTOGRAPIIER, Presentation Prints—Mr. Fax’s Mode or Masking—Pho tographic Exhibition—Photographers' Relief Fund— False Reports—Societies. It has often struck me that the distribution of presenta tion prints is one of the most useful, as well as one of the most pleasant, of the duties of photographic societies. If the office of the committee of selection be exercised with judgment, the prints so distributed may possess a highly educational character. Examples of novelty in process, of skill in mechanical or chemical treatment, or excellence in art, thus distributed by societies, often teach more forcibly and practically than many papers or the discussions thereon. The North and South London Societies have both admirably carried out this function of a society. They have both been amongst the first to present examples of carbon printing to their members. They have both aimed at giving examples of the work of the great masters in photography, men who excel alike in the technical and the artistic qualities of their work. I find the names of Bedford, Mudd, Rejlander, Robinson, Lake Price, Blanchard, Bingham, Wilson, Vernon Heath, Frank Good, Cherrill, and Woodbury amongst those whose works have been distributed amongst the members of these two societies. The last distribution of the North London Society is surely the most extraordinarily liberal one which was ever made under similar circumstances. Let it be remembered at the outset that the subscription to this Society is but half a guinea a year, and that after the payment of necessary expenses the balance only can be devoted to the purchase of presentation prints. The prints distributed this year must, however, estimated commercially, have been worth three or four times the amount of the annual subscription. First, there was a magnificent 12 by 10 subject-picture by Lake Price, entitled “ The Falconer,” never before published; next, a IG by 12 landscape by Mr. Cherrill, with the most glorious clouds ever produced, I think, in so large a photo graph ; and next, two whole-plate studies by Rejlander, printed by Woodbury's process. All these were mounted on good cardboard—not plate paper—with India tinted mounts. The South London present their members with one of Rej- lander's charming studies, and a splendid carbon print, 16 by 12, fiom one of Robinson’s subject-pictures. The members of the London Photographic Society have their prints yet to receive; but prints from Mayall, England, and Robinson are promised. The suggestion of Mr. Fry for a novel mode of masking is very ingenious, and may doubtless, in many cases, prove eminently useful. A photographer will, of course, always try to produce harmonious negatives, through which the printing of all parts will go on in due order, without mask ing or retarding in any part; but, despite the greatest skill, over-dense negatives will sometimes be obtained, and special subjects will at times present special peculiarities which render masking imperative, and the transparent positive undoubtedly presents the best bases for a mask which can possibly be obtained. I say bases for a mask, because I apprehend that, in the majority of instances, the photo grapher of taste will see something in the light and shade of his picture which may be modified and improved by working on the mask. I have been gratified to find generally prevailing amongst photographers whom I meet a pleasant anticipation ot the forthcoming exhibition of the Photographic Society, and of the social runion with which it is to open. It seems to be a general opinion that the easy absence of formality which prevailed at the last exhibition meeting rendered it much more agreeable than a conversazione at which evening dress is de rigueur. I look forward with interest to the display of pictures, especially in the department of por traiture, in which I expect to see a considerable revolution
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