The photographic news

• Bandzählung: 29.1885
• Erscheinungsdatum: 1885
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-188500006
• PURL: http://digital.slub-dresden.de/id1780948042-18850000
• OAI: oai:de:slub-dresden:db:id-1780948042-18850000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
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• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

FEBRUARY 20, 1885.J THE PHOTOGRAPHIC NEWS. 117 photograph ; near objects are larger, and distant objects smaller, than they should be in relation to each Other. This is owing to the fact that the lens does not see as the human eye sees ; no lens has absolute depth of focus, and as the scale of picture is determined with any given lens by the back.focus, it follows that if the focus for distant objects is less, then the focus for near ones with the same lens, the relative proportion will vary in ratio to the difference of focus. The landscape lens has the greatest depth ot focus, but it gives spherical aberration, that is, from the centre of the plate it gradually resolves all lines into a sphere. This is very little apparent if objects with straight lines are kept out of the picture ; but though we avoid straight lines, and photograph things which are curved, still the aberration is there, and is altering the curved lines exactly as much as it would alter the straight ones ; so if the subject photographed was a very perfect combination of curves, such as a mountain outline, stretching from side to side of the pictures, they would be altered in their form in the photographic landscape. To get over this difficulty, lens makers made a combination of lenses, placing a piano convex lens opposite another plano-convex lens, so that the lenses acting contrary to each other bend the lines sufficiently into their right form ; but to secure this, depth of focus is sacrificed, so that with the symmetrical or rectilinear lens the photographer is restricted within the limits of the lenses’ capacity. In the experiments 1 have made, I find that if in photographing architectural subjects we keep the nearest object about ninety feet off, and do not include a great difference in the distance of one object from another—that is, do not include a great depth of focus—the traced outline from nature almost coincides with the photograph. It is when we try to include great distance with near foreground that the difference becomes apparent. Now if we bear this in mind, and consider how differently scenes present themselves before us, we shall see that with this restriction, many of the most beautiful combinations of line composition in nature cannot be reproduced satisfactorily in the photograph, for it often occurs that the beauty and composition of a view depond on a system of lines beginning very near to the spectator, and grouping themselves and harmonising with the distance. The photographer, placed before a scene which is beautiful in com position, has to consider the capabilities of the lens, and ask himself, can this be photographed I but the artist has no con sideration of this kind coming between him and nature, lie can transfer the scene to his paper or canvas without hindrance. Now, this tendency of the lens to dwarf magnitude is in direct opposition to the artistic mind, for artists feel that a mere topo graphic copy of a scene, line for line, and tint for tint, will not give an impression of the breadth, vastness, and magnitude of nature, therefore they use their art power, and arrange their lines and gradations of shade in such a way, that every line and shade will have its use in the composition, and if, after all this, he feels that his picture will not give the same impression of size and magnitude as nature, he will represent things larger in pro portion, so that they may convey the same sense of largeness as nature ; this you will see in working in the opposite direction to the photograph. And now I will draw your attention to the different ways in which an art critic considers a picture, to the way in which photographs are judged at our exhibitions. The art critic looks for correct drawing, the relative masses of light and shade, breadth, composition, and, above all, to the evidence there is in the picture of the mind of the artist. Now I want you to notice that I do not include in this list of excellences that of detail, for the artist, according to his subject, has to sacrifice detail in order to attain higher truths. Now, if we turn to the photo critic, we find he first of all looks to see if there is what is called sharp focus, perfect definition throughout, and if this is found wanting, the photo is straightway condemned as not possessing the first quality in photography ; but if the photo stands this crucial test, then he goes on to examine it as to composition, choice of sub- ct, point of sight, and light and shade. He cannot look for breadth, because the demand for definition and detail destroys it. Perhaps it may stimulate comparison of the different ends aimed at by the artist on the one hand, and the photographer on the other, if I give for your consideration a well-known paradoxical description of sunrise, by the great French painter Corot. Referring to the mystery and indefiniteness of masses rising against ihe sky at the first blush of dawn, he exclaims, ‘ I can see nothing—everything is there 1 ” And referring to the later excess of detail revealed by the broad common daylight, he cries, “ I can now see everything—but nothing is there! ” TRANSPARENCIES. BY T. N. ARMSTRONG.* When the season for out-door work closes, amateurs begin to look about for means of employment during the dark evenings. There is, fortunately, no necessity for being idle, or to relinquish photographic pursuits entirely, even though the weather and light combine to render out-door work almost impracticable ; and most amateurs will be found to have some hobby or favourite amusement which enables them to keep in practice during those months when many channels of employment are closed to them ; and probably one of the most popular, as well as the most pleasing, occupationsis the production of transparencies for the lantern. It is not my desire to enter into any discussion as to this or that being the best means of producing these delightful pictures, but merely to describe a way by which a pleasant evening can be spent at photography, and slides produced of much excellence by artificial light. To-night I propose, by the aid of artificial light, to make a few slides with Beachy’s dry plates. On the whole, I have been most successful with them, and have obtained results more satisfactory than by any of the other processes I have tried. I do not say that results quite as good canuot be obtained by any other method, for I know manipulative skill plays a most important part in this class of work. When I first took up the making of transparencies with wet collodion, I was told that my sorrows would not be far to seek, and so 1 soon found out. Need I tell you of all my failures, such as films floating off the glass, oyster-shell markings, pin holes, films splitting when dry, &c., &c., not to speak of going to business with fingers in fearful state with nitrate of silver and iron developer ? Now all these miseries have gone, and I can, with dry collodion plates, work with the greatest of comfort, and obtain results quite equal to the best productions of any method. It may be interesting to some to know the formula by which the emulsion is made, and as the making of it is by no means a difficult operation, I may be pardoned if, before going fully into the more practical part of my paper, I describe the formula, and also the manner in which I coat and dry tho plates. The formula is as follows, for which the world is indebted to Canon Beechy :— In 8 ounces of absolute alcohol dissolve 5 drachms of anhy drous bromide of cadmium. The solution will be milky. Let it stand at least twenty-four hours, or until perfectly clear ; it will deposit a white powder. Decant carefully into an 8-ouuce bottle, and add to it 1 drachm of strong hydrochloric acid. Label this “ bromide solution ; ” and it is as well to add on the label the constituents, which will be found to be nearly— Alcohol ... ... ... ... ... 1 ounce Bromide of cadmium ... ... ... 32 grains Hydrochloric acid .. ... ... ... 8 drops This solution will keep for ever, and will be sufficient to last two or three years, and with this at hand you will be able in two days to prepare a batch of plates at any time. In doing so, you should proceed thus :—Make up your mind how many plates you mean to make, and take of the above accordingly. For two dozen ^-plates or four dozen 8] by 3} dissolve by heat over, but not too near, a spirit lamp, and by yellow light, IO grains of nitrate of silver in 1 ounce of alcohol ’820. Whilst this is dissolving in a little florence flask on a retort stand at a safe distance from the lamp—which it will do in about five minutes-—take of the bro- mized solution } an ounce, of absolute ether 1 ounce, of gun cotton grains ; put these in a clean bottle, shake once or twice, and the gun-cotton, if good, will entirely dissolve. As soon as the silver is all dissolved, and whilst quite hot, pour out the above bromized collodion into a clean 4-ounce measure, having ready in it a clean slip of glass. Pour into it the hot solution of silver in a continuous stream, stirring rapidly all the while with a glass rod. The result will be a perfectly smooth emulsion without lumps or deposit, containing, with sufficient exactitude for all practical purposes, 8 grains of bromide, 16 grains of nitrate of silver, and 2 drops of hydrochloric acid per ounce. Put this in your stock solution bottle, and keep it in a dark place for twenty-four hours. When first put in, it will be milky ; taken out, it will be creamy ; and it will be well to shake it once or twice in the twenty-four hours. • Abstract of a paper communicated to the Glasgow and West of Scotland Amateur Photographic Association.