The photographic news

• Bandzählung: 13.1869
• Erscheinungsdatum: 1869
• 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-id1780948042-186900000
• PURL: http://digital.slub-dresden.de/id1780948042-18690000
• OAI: oai:de:slub-dresden:db:id-1780948042-18690000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Bemerkung: Heft 545 (S. 73-84), Heft 547 (S. 97-108), Heft 589 (S. 599-610) fehlen in der Vorlage. Paginierfehler: Auf Seite 444 folgt Seite 443
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• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

40 THE PHOTOGRAPHIC NEWS. [January 22, 1869. factured in London which do not melt, but burn, and are, therefore, specially suited to the purpose. According to the Photographische Correspondenz, the Sultan has just conferred upon M. Friedrich v. Voitlander the decoration of Officer of the Order of the Medjidie, in appreciation of the valuable services rendered by that gentleman. The same journal contains the text of a series of inter esting lectures upon photographic chemistry, delivered by Or. E. Hornig at the Imperial Polytechnic Institute at Vienna. Dr. Hornig carefully goes into the history of the art, and details with much accuracy the early experiments by Charles, Davy, Wedgwood, Hooper, Young, Niepce, and Daguerre. He also gives a resume of the progress of photography, its adaptation to metal plates, to paper, and to glass. M. Edmond Becquerel has just published a work entitled “ La Lumire, ses Causes et ses Effets,” in two volumes, the first of which treats of the sources of light, while the other details its effects. The book is a very complete treatise of what is at present known of the subject, and the writer has gone into even the most minute details in respect to photography. A chapter upon photography in colours contains an account of the researches and experi ments which have been made in that direction, and the whole work is illustrated with many original woodcuts and engravings. PHOTOGRAPHY IN HOT CLIMATES: Especially its Employment for Taking Views of Buildings and Dark Interiors. BY DR. H. VOGEL. When I was taking partin the expedition for astronomical and photographical observation of the eclipse at Aden, in South Arabia, as well as in the archaeological photographi cal expedition for taking interesting interiors of Upper Egypt, I had opportunity for making a series of observa tions which are of much practical interest to the photo grapher, and which I propose to communicate briefly to the reader, expecting that I may give some valuable hint not only to the photographer in tropical countries, but also to our compatriots; for, as we have seen in the summer of this year, some European climates may become sometimes very similar to that of the torrid zone. To the photographer who works in a hot climate several difficulties arise in an intensified degree which we are troubled with in operations in our country, as, for instance, dry spots, fogs, insensibility of margins, which are commonly ascribed to the high temperature alone ; but my experience at Aden and in the desert has taught me that the amount of moisture present in the air plays a very important part too. In the atmosphere at Aden, highly saturated with moisture, I was allowed to expose wet plates without any further precaution for twenty minutes, at 269 Reaumur (90-5 Fahrenheit), without having to fear dry spots. In the dry air of the desert, however, I had dry spots at the same temperature and with the same chemicals after six minutes. At Aden long exposure offered, therefore, but very little difficulty, whilst in the desert and in the valley of the Nile, enclosed on both sides by the desert, they exhausted my patience. Similar observations will be made in Europe in hot months, and it will be found wise to take our precautions according to the amount of moisture con tained in the atmosphere. First, a few remarks about the Apparatus.— During .my longer operations in very dry and very hot districts of Upper Egypt I observed that apparatus constructed of wood—as cameras, tripods, &c.— very soon became so dry that the planks warped or burst. From this cause a large new tripod, the camera, and especially the small objective boards, were nearly made useless. In order to avoid this trouble, all wooden parts are to be sheeted with metallic bands, which prevent the boards from separating, but not from warping and shrink ing. I secured the same end by putting into the camera, even when it was not in use, a piece of wet sucking-paste, and covering this with a wet cloth. We may also moisten the hcad-cloth, and we shall perceive that under it the heat is very much diminished. For the same purpose the cloth of our tent was often moistened from the exterior. We employed a camera constructed by Mr. Meagher, London. It could be distended from two to twelve inches, allowed of employing objectives with very short focus, stereoscopic plates to plates of 8} and 6} in any situation, and was very portable. For taking architecture, especially very elevated details, as friezes and relievos, we employed, besides an ordinary tripod, a very large one, the feet of which consisted of three parts which could bo taken to pieces ; its height was twelve feet. By taking off the upper part it was shortened to eight feet. For taking ceilings, &c., it is necessary to employ the camera in a vertical position. We therefore screwed it to the side of one of the legs of the above-mentioned tripod stand, and this latter placed into proper position, with the lens pointing upwards. Canting of the tripod was pre vented by the heavy weight of the feet, which could be increased still more by large stones. It is always, in my experience, preferable to employ a heavy tripod-stand; the more solid its construction the better it will resist the wind. The small English tripods are so much shaken by the breeze that photographing is very often impossible. Our tent was one of Mr. Rouch’s construction. Objectives.—With our operations we were often obliged to take a view of walls covered with inscriptions and re lievos which were but very weakly illuminated. In such cases it is of importance to employ an objective which, with a large aperture, gives a bright image with details to the very margin, in order to get a clear pic ture in a proportionally short time. Steinheil’s aplanatic lens proved most suitable. No. 3 of this lens afforded sufficiently sharp images of 7 by 9 when we employed the second stop. It has, compared with other archi tectural lenses, a large aperture (one-seventh of the focal length), and a flat field. Besides this lens we employed also Busch’s triple and pantoscopic lenses, and Dall- meyer's triplet and wide-angle lens, when we had a suffi cient amount of light. All objectives gave pictures of 7 by 9, but their focal length differing from 4 to 10, they were employed alternately, according to the distance of our point of view from the object. The Light.—The very weak illumination of the Egyptian temples and tombs often obliged us to take our refuge to a remedy till now little employed in photography. Whenever it was possible, we increased the illumination by reflected sunlight. This means is a very excellent one, especially in Egypt, where there is no want of sunshine. We employed two ordinary mirrors of 4 inches in size. Two persons held the mirrors in this manner so that the sunbeams were reflected to the object which was to be taken, and by slowly moving the mirrors during the ex posure the illumination was made as even as possible. Dark spots of the object naturally received the sun rays for a longer while than light ones. With Steinheil’s lens, six or seven minutes’ exposure sufficed for taking such objects, and even a shorter time would have done if we could have disposed of better reflectors. Where this means could not be employed we made use of magnesium light, which, however, requires a very actinic objective. Our lens was a portrait lens, with full aperture. Naturally, we got but a very small field of suffi cient sharpness, so that we could only take a plan of six inches size. It is necessary to approach the magnesium lamp to the objects as near as possible, but also to take care that the natural disposition of light and shade is not spoiled. It will also be very useful to move the lamp during the exposure, so that all parts of the object are equally illuminated, and to provide for wind, to remove the