The photographic news

• Bandzählung: 35.1891
• Erscheinungsdatum: 1891
• 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-id1780948042-189100009
• PURL: http://digital.slub-dresden.de/id1780948042-18910000
• OAI: oai:de:slub-dresden:db:id-1780948042-18910000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

THE PHOTOGRAPHIC CONVENTION. “ CONVENTION week is generally wet,” was a common remark heard at Bath last week, but, as a matter of fact, the weather cleared up after Wednesday, and for the rest of the week the members of the Convention had little to complain of in the matter of weather. The Convention Group on that day was taken in a pouring rain, and Mr. Ashman had to give the word to lower umbrellas, just as if he had been in command of a battalion of soldiers, and had directed them to present arms. Many pictures of the members were taken, for, in addition to Mr. Ashman’s camera, there were many others in position. This very wet trip to the Sydney Gardens, where the group was taken, constituted the sole excursion on Wednesday, which was, with this exception, devoted to business in the Guildhall. We have already recorded that a general meeting was held earlier in the day. In the afternoon, Mr. W. Lang, jun., F.C.S., read a paper, with illustrations, on “The Photographic Work of Herschel and Fox Talbot,” which will be found on another page of our present issue. In the course of a few remarks in the discussion which followed, Mr. C. H. Talbot, a son of Mr. Fox Talbot, said there could be no doubt whatever that his father obtained definite photographic results in 1834 and 1835. He possessed a few views which he believed to be of the year 1835, but, unfortunately, conclusive proof of this was not forthcoming; but he judged their date from the fact that his father had stated that his earlier views of 1834 and 1835 possessed the characteristic of having (as was the case of the ones in question) their outline come out with dis tinctness ; but the details were indistinct, and, therefore, differed from views dated 1839. There was another specimen of a fern leaf upon paper, of which the water mark was 1835. He should have pleasure in showing these views, and other unique examples of early photo graphic work produced by his father, to the members of the Convention who visited Lacock Abbey on Friday. Mr. Lang’s paper, which was much applauded, was followed by one by Mr. C. H. Bothamley on “Recent Developments in Printing Processes,” which we print on another page, his remarks being rendered additionally interesting by a number of capital illustrations. The experiments were watched with great interest, and at the close Mr. Bothamley was heartily thanked. Mr. J. Traill Taylor then read a paper, written by Mr. Debenham, on “ The Cult of Indistinctness.” There was a large attendance at the evening meeting, when Mr. A. A. Common, F.R.S., favoured the company with numerous illustrations of recent astronomical photo graphy shown on the disc by Mr. Pringle, and graphically explained by the lecturer. The photographs included representations of nebulae, the planets Jupiter, Neptune, &c., and photographs of the moon in different stages, these latter showing a wonderful amount of detail. The lecturer was warmly thanked for his extremely interesting remarks and pictures, and the meeting terminated with the dis cussion of one or two matters of interest to the Convention. On Thursday the members of the Convention divided their favours between Salisbury and Bristol, to both of which places there were excursions, returning in good time for the meeting at the Guildhall in the evening, where there was a large attendance. The chair was occupied by the President (Mr. Bedford), and Mr. A. Haddon (Royal Naval College, Greenwich) presented the report of the Lens Standard Committee appointed to consider the adoption of standard lens fittings and take steps necessary for their effective establishment. The report was a sup plementary one to that submitted at Chester last year. It appeared that immediately after the last Convention the secretary of the committee appointed by the Photographic Society invited the committee to join them and consider standards with regard to lenses, and objections to certain others. The Photographic Society of Great Britain had adopted most of the suggestions which the committee at Chester made, and satisfaction was expressed at the fact that difficulties with the leading opticians had been over come. Mr. Bothamley proposed the adoption of the report, and congratulated the committee upon the accom plishment of what might be regarded as the most important work the Convention had yet taken in hand. It must also be satisfactory to know that the recommendations contained in the report had met with the approval of the leading opticians of the world, and that the committee was in agreement with the Photographic Society. Mr. Levy seconded. In the discussion which ensued, Mr. Warnerke spoke as follows :— There is one point in the recommended standard I wish to direct the attention of the Convention to—viz., the unit of the rapidity of lenses. Some ten or twelve years ago the Photo graphic Society of Great Britain chose f/4 as the unit, and it is also recommended now by the committee of the Convention. The ten or twelve years that have elapsed since the introduc tion of that unit is certainly long enough time to look back and examine what is the practical outcome of that measure. Con stant readers of our numerous publications cannot but observe that whenever the question of rapidity of the lenses occurs, the numbers of the unit standard are not used. The present meet ing of the Convention offers an excellent field to verify the popularity of the measure. During our numerous excursions, when everybody is busy using his camera, the most natural question in conversation is, what diaphragm do you use ? This question invariably has been answered, f/10 or f/6, &c. Even members of the past and present lens committee, and opticians marking their lenses with unit standard numbers, do not use them when answering this constantly recurring question. Certainly there must be something in the measure pro posed that is not practical. In reality, this standard is not the best, and that, I think, is the reason why it is not practically adopted. It requires too much calculation that cannot be accomplished without pen or pencil. There are two other units — f//10, proposed by Mr. Dallmeyer, and f/10, adopted by the Paris Congress. To find the unit standard number for a certain diaphragm, it is necessary to find the square of the fraction representing relation of focus to the diameter of aper ture of that diaphragm, and divide it by the square of unit diaphragm—viz., by 16 in the case of the proposed unit, by 100 for French unit, and by 10 for Dallmeyer’s unit. It will be readily seen that division of any number by 10 or 100, requiring only removal of the decimal point, is much simpler than division by 16. However, this is not the only plea in favour of f/lO as a unit. We are going to the Brussels Congress, and certainly it will not be becoming to English photographic societies to propose a measure that is not the very best, and consequently one that has no chance of being adopted universally ; f/10 is better than fli, because it is simpler. It is already adopted by the Paris Congress, and it is clear that for these two reasons it will have all Congress in its favour. Supporters of f/4 unit put forward an argument that some opticians have already adopted the system for marking their lenses, and that any change of the system will put them to inconvenience. To that I can answer—and that not only on supposition, but as the result of inquiry—that those who have adopted already f/i will adopt without hesitation any other system recommended as best by recognised authority. There is also a great deal to be said respecting the system of