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The photographic news
- Bandzählung
- 29.1885
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- 1885
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- Hochschule für Grafik und Buchkunst Leipzig
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- Bandzählung
- No. 1395, May 29, 1885
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Zeitschrift
The photographic news
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Band
Band 29.1885
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- Register Index III
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Band
Band 29.1885
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May 29, 1885.] THE PHOTOGRAPHIC NEWS 349 but if the distinction therein given were generally accepted, we should be saved a considerable amount of annoyance at times when the exact meaning of a writer is ambiguous. “ A photo-micrograph,” says this authority, “ is an enlarged representation of a microscopic object, produced by throwing its image through a suitable combination of lenses, as of a micro scope, on a sensitized plate.’ ’ “A micro-photograph,” says the same authority, “isa photo graph of proportions so minute that it requires to be examined by the microscope.” Here we have the difference clearly and distinctly defined. Each term was so recognised and used by the late Colonel Dr. Woodward, the most eminent worker in photo-micrography the world has yet seen, and it is to be hoped his successors will follow where he led. It may not be amiss to recall the incidents attending the pro duction of my first negative of a microscopic object. For some months previously my spare moments had been devoted to the fascinating work of out-door photography with gelatine plates, which I had pursued with all the ardour, common to a novice, so well known to all of you. My first essay was made with the so- called pocket camera of Walker, a little square box without bellows, carrying a plate 2 by 84 inches, the focus being ad justed by sliding the tube carrying the single achromatic lens. With this little box very fair work may be done, and I produced many negatives which were a source of pride and pleasure. The advent of winterish weather seemed to forbid further out-door work ; interiors were unsatisfactory, and the camera was reluc tantly laid aside to await the advent of another summer. One evening, whilst engaged with the microscope, the thought suddenly occurred, why not try to make a photograph of that object ? This happened to be the small eyeless flea of the mole, not a very perfect specimen, having lost several of her feet, and not at all adapted to a beginning in photography (as I after wards learned), having a thick, yellow, chitinous skeleton, rather opaque, although mounted in Canada balsam. The objective in use was beck s 19 inch, first-class series, with 10-inch tube, in clined at an angle of 45°, and an A eye-piece ; illumination, the light of a German student’s lamp, reflected by the concave mirror of the microscope without any condenser. I found that upon removing the cap of the microscope ocular and the lens tube of the camera box, the outer tube of the latter exactly fitted over that of the former, holding the camera in place, and revealing to my delighted eyes a small but perfectly defined im age of the specimen on the focusing screen. To transfer this to a sensitized plate was now the problem I had to solve. There was absolutely no guide procurable ; nothing had been pub lished, so far as I knew, on the subject as connected with gela tine plates and lamp-light illumination. Experiment alone must be my teacher. The character of plate suitable, with length of exposure adapted to the object, could only be deter mined by actual work. Choosing the most sensitive plate in my possession (Carbutt’s J. C. B.), an exposure of five minutes was given, and develop ment with ferrous-oxalate followed. I will say nothing of my feelings as I watched the latter and the growth of the image. You have all made your first negative. The exposure proved to have been correct; a clear, clean negative of proper density was the result. But where was the crisp shai pness of outline and detail so clearly seen when examining the object through the ocular in the microscope itself, or its image upon the ground glass ? This negative was sadly wanting in sharpness. I was certain that focussing screen and plate holder registered exactly, for the Walker camera is very accurately made, and my out door negatives had all been sharp and crisp. Suddenly I re membered having read that all microscope objectives of powers under one-fifth of an inch require special correction to render the visual and actinic foci coincident, which correction had not been applied to the objective now employed. Thus the mystery of a sharp image on the ground glass, and a dull one on the gela tine film, was solved. The Messrs. Beck have since made for me a series of object glasses from four inches to four-tenths of an inch focus, corrected for photographing, and their performance on all classes of sub jects is perfectly satisfactory. From a quarter-inch upward to the highest power I have employed, no special correction has been necessary. From the negative (the making of which has just been described) I have printed a positive, which will be shown on the screen this evening, together with another made from the same specimen with a corrected 1J inch, and an ex posure of ninety seconds on a slow plate, leaving you to make your own comparisons as to the advance made since that first exposure. (To be continued.) Oorxespondente. MR. A. PRINGLE ON JUDGING PHOTOGRAPHS. Sin,—May I ask you as a favour to give publicity in your columns to the following correspondence ? I abstain for the present from all comment on this matter, confining myself to the statement that each of my “ suggestions ” has been framed with a view to meet one or other of the flaws or irregularities in the past system of judging noticed by me when acting as a juror last year at the Exhibition in Pall Mall. I place my case in the hands of the public, asking that public to judge between the council and me, to say in your pages whether or not my suggestions are reasonable, and to decide whether or not the public will demand the attention which has been denied to me by the council. If anyone accuse me of a desire to hurt, or detract from the influence of, the Photographic Society of Great Britain, he accuses me falsely. Now that we hear of pseudo-amateur societies springing up, ostensibly repre senting amateurs, but really representing commercial interests only, so far as I can discover, it is high time that the Society should place itself in a position sans pew el sans reproche, and that its members should take steps first to perfect, and next to perpetuate, what really ought to be the representative society not only of amateurs, but of professional photographers all over the kingdom. ANDREW PRINGLE to W. F. Donkin, Esq., lion. Seo. P.S. of G.E. Dear Mr. Donkin : Official. Herewith I send you a communication addressed to the Presi dent and Council of of the Photographic Society of Great Britain, and I have to request you to lay my letter before your Council at the first opportunity. If I have no reply after a period of one week from the date of your second council meeting after this date, I shall understand that the Council declines to pay any attention to my suggestions.—I am, yours very truly, (Signed) Andrew Pringle. The date of this was March 28th, 1885, and since then the Council has had two meetings, the latter being on the 12th of the current month, May 1885. I have—now that much more than the time allotted by me has elapsed—got no reply of an official nature, nor have I any official notice of my suggestions having been even considered by the council. My only course, therefore, is to publish my suggestions, which I now proceed to do. The following accompanied my letter to Mr. Donkin already repro duced :— To the President and Council of the Photographic Society of Great Britain. Gentlemen,—Having last year a slight insight into the system of judging at our Exhibition in the Society’s Rooms in Pall Mall, and also at an exhibition under different regulations in another place, I beg, with diffidence of myself, but with full confidence in you, to offer for your consideration a few points that I think might with advantage to our Society be noted for future guidance. The object of my suggestions is not to prevent future groundless dissatisfaction, which appears to be inevitable, but to avoid ground for dissatisfaction. 1 purposely, for reasons that you will appreciate, delayed my approach to you till after the closing of our annual exhibition for 1884, and until I should have a chance of forming an opinion by comparison with other systems of awarding prizes. With your permission I will put my suggestions categorically. 1st. Each juror should carefully examine and allot a value to each frame in the room, and should sign a paper stating on his word that he has done so; this paper to be attainable to the public. And every person elected by you to act as a juror should, before his election is confirmed, undertake so to examine each frame. 2nd. Each juror should, at the completion of the judging, sign the medal-list, not necessarily attesting his entire, but Usgtniral,
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