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
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OcTOBER 30, 1885. | THE PHOTOGRAPHIC NEWS. secure it by using higher power in the objective. Do not attempt to make great blurred images by removing the sensitive plate to a great distance. With your screen at a distance of two feet from the microscopic stage, employing a first-class one- eighth inch objective, you may get from 800 to 1,000 diameters, ample for your twelve months’ work. Indeed, I would advise beginning with a good quarter-inch objective and about eighteen inches distance. In ordering our steps, you may have noticed that I removed the eye-piece, and I mean to keep it so removed. I have never seen an instance where the introduction of the eye-piece was desirable; and I have seen a great many errors and imperfec tions introduced by the employment of it. If, however, you will insist on using the eye-piece, let me caution you—see to it that no speck of dirt, however small, remains on either lens, for the slightest fleck of dust is sufficient to make an ugly mark on the negative. This precaution should prevail with the mirror surfaces as well. Let them be thoroughly cleaned before com mencing your day’s work. Now, how long shall I expose ? No earthly intelligence can answer this question for you. You will, after a time, be able to look at the image on the ground glass, and judge with a con siderable accuracy as to the length of exposure ; and it is just this experience alone which will enable you to so judge. With our present facilities, and with moderate amplification, the drop- shutter can be used—although it is better to diaphragm down the light and expose longer. The best exposer is a little flap of velvet hanging over the eye-piece end of the microscope tube, as it may be lifted and the exposure made without danger of dis turbing the adjustments. When it is not required it is turned aside, and so held by a hook-and eye. Now, in what way can we modify our apparatus, and lessen the expense without materially affecting the final result ? I am perfectly assured of one thing: for results that will prove satisfactory to the conscientious amateur, I believe that the darkened room cannot be dispensed with. Anything short of this is shaky and unreliable, besides tedious, in consequence of the endless running to and fro, from the stage of the micro scope to the screen of the camera. With our gelatine plates, for a very large range of work, the heliostat can be dispensed with. It is a luxury, and indispens able if very long exposures are necessary. But a great deal of work can be done with the secondary mirror alone, although the constant adjustments are tiresome. The next absolute luxury—and this is purely so—is the ex pensive mechanical stage. If the student is prepared to draw liberally on a very large stock of patience, the mechanical stage may be omitted. The modern glass stages, moving, as they do, easily, and with ready control, answer fairly well for the more expensive attachment. The centering sub-stage for first-class work cannot be spared. Much low-power work can be fairly done with a plain sub-stage, however. (To be continued.) Correspondence. A GOOD SODA DEVELOPER. Dear Sir,—Does Mr. Wilkinson mean bicarbonate (NaHCO,) of soda? as lie says Howard’s make. He calls it carbonate (Na,CO,10H,0) ; I never heard of this as Howard’s.—Yours faithfully, An Old Amateur. 2roceedings of Societies. Photograi’iiic Society of Great Britain. A technical meeting of this Society was held in the Gallery, 5A, Pall Mall East, on Tuesday last, the 27th inst., Captain Abney, F.R.S., in the chair. The Chairman having stated that improvements in apparatus exhibited on the tables would bo explained, called upon the following gentlemen, or their representatives, for short descrip tions of the novelties claimed. H. and E. J. Dale showed the action of their ‘ patent adjustable shutter,” with pneumatic regulation for timing exposure. Either one of a series of holes, situated at the top of a metallic tube, permitted an escapement of air—the larger the hole the quicker the action of shutter. The multiplex back and camera previously described were then shown, as well as an adaptation of the electric light for dark-room and developing purposes. A couple of five Volt lamps were used, one white and the other ruby, 3-candle power being obtained. The battery was said to be capable of running three months; it was a form of potassium dichromate in which the second liquid employed was ammonium or other chloride. The Chairman enquired how long the battery would work without polarisation, and he was informed that something like twenty hours’ work might be expected from the cells, and that amount of energy could be extended over three months. Lieut.-Col. C. D. Durnford’s printing-frame was then shown. It resembled the back of an ordinary printing-frame, the springs being arranged to clip over the edges and secure a negative firmly on the inside. W. J. Stillman explained the action of the Eastman-Walk er roller slide and film-carrier, a detailed description of which will be found on page 324 ante. E. Cocking spoke of the desirability of an indicator other than the present, which causes four distinct clicks to be the signal ; and, in reply, he was informed that the Eastman Com pany are now adding a visible signal to their roll-holders. T. Samuels remarked that he had noticed certain marks in negatives made by means of the roller slide which did not appear when cut films were used, and he thought that they arose from the great tension put upon the rollers. The Chairman had seen similar marks in some negatives shown him by S. G. B. Wollaston. Twenty-four negatives, 8 by 6, the result of as many exposures on one band of paper, were then shown, and these Mr. Stillman said had been made by himself without a failure. He doubted whether he could have done so well with glass plates. The Assistant Secretary next explained a new actinometer, in which the illumination was reduced to the deepest shadows in the camera. T. FURNELI. showed a new instantaneous shutter, the advant ages being that the exposure to the foreground could be in creased and the sky diminished at will; long or short exposures could also be given. The “ New Simplex Camera ” of Hopkins Bros, was next called attention to. In this instrument the dark-slide fits on the top of camera, and the plate is pushed down into position by means of a rod. There is a convenient plan of disposing of the focussing screen when out of use, and the camera possesses all the swing movements, while a half-plate specimen shown ranges from about two and a-half to sixteen inches in focus. Mathew Whiting’s “ Patent Lantern Slide Holder ” followed. In this ingenious contrivance, most readers will remember, Mr. Whiting has two boxes or hoppers attached to the carrier proper. The slides are pressed into the carrier by means of a spiral spring, and after passing through the lantern are safely packed into the second box. The Patent Combined Camera Back of H. Mader, for use with a metallic plate envelope instead of slides, was next shown ; the envelopes seemed very handy, and were said to be quite safe as regards light. Marion and Co.’s exhibits were described by E. C. SPICKER- nell. They comprised a new shutter, by Cadett, for various exposures, which was set by winding up a spring. The Middle- miss patent camera, the focus of which extends from 5 to 30 inches, followed, the short focus being obtained by an ingenious plan of bringing the back portion forward. Then came an explanation of their print-washer, with porcelain trough, which was said to wash prints perfectly in half an hour. The com- pacta camera and envelopes for the same followed. These latter were exceedingly light, and will, no doubt, find favour with tourists. The camera is reversible, and has both a side and back swing. Wollaston’s diaphragmatic shutter was then shown by the inventor, and he stated that he could regulate the speed to anything between 13gth of a second to upwards of eleven minutes. In twenty trials the variation had not been Ith of a second. The Chairman enquired if it would be necessary' to have more than one shutter fora series of lenses ; and, in reply, it was said that most of the usual rectilinear type of lenses, especially Ross’ working up to 8 by 10 plates, would answer for the shutter he was showing. Urie’s automatic exposing apparatus was next described by Marion and Co. The “Alpha” paper passes from one spool