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The photographic news
- Bandzählung
- 12.1868
- Erscheinungsdatum
- 1868
- Sprache
- Englisch
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- F 135
- Vorlage
- Hochschule für Grafik und Buchkunst Leipzig
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- Hochschule für Grafik und Buchkunst Leipzig
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- SLUB Dresden
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- Public Domain Mark 1.0
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- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
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- Bandzählung
- No. 504, May 1, 1868
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Zeitschrift
The photographic news
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Band
Band 12.1868
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- Titelblatt Titelblatt I
- Kapitel Preface III
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- Register The Index To Volume XII 619
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Band
Band 12.1868
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216 THE PHOTOGRAPHIC NEWS. [May 1, 1868. EARNEST.—In using a stereoscopic camera with one lens and Latimer Clark’s sliding bars, the principle to be borne in mind is, that the camera must, in moving laterally, describe an arc of a circle of which the sitter or object to bo taken is the centre; and the bars must be adjusted to different degrees of convergence for different distances, in accordance with this principle. When this is properly done, you will have no trouble in securing images which Will combine. To assist in adjusting, mark the size of the picture, forming one-half of the slide when mounted, on the ground glass; focus the subject so as just to come within the lines when the camera is placed at one extremity; then move it to the other ex tremity, and if the adjustment bo correct it will again just come within the space marked. It is the ratio of convergence rather than the length of the bars which regulates the proper position. Thanks. W. J. A. G.—With the aid of a lens, using one eye, you obtain ■such an effect of relief as can be represented by light and shade; with the aid of the stereoscope on a properly produced slide, you get such an actual perception of relief as can be obtained by using two eyes, and so obtaining a view of two sides of an object; and the stereoscope is of no service in examining a picture which has not been taken from two distinct angles, such as those seen by the right and left eye. In using one eye, if the head were held perfectly still, no perfect conception of relief and distance could be formed; but nature is very beneficent, and readily provides compensations: by moving the head slightly, a view of all objects around, from two points similar to that seen with two eyes, is obtained. Where a person has not the good fortune to possess the use of both eyes, this means of compensation is unconsciously and valuably used ; but the use of the stereoscope is one of the things, unfortunately, under such circumstances, quite lost. 2. The spot in the centre of the negative, under the circumstances you describe, is flare; its cause has been the subject of much discussion. It is believed by the best authorities to be an image of the stop, very much out of focus. It is chiefly found in portrait and similar combinations, and is most annoying where long exposures are necessary. Using a stop in front of the lens aids in getting rid of the spot, as also pro tecting the lens from the full light of the sky by shading it during exposure. 3. The photograph enclosed is very good indeed, and the tone excellent. G. C. C.—The pink tone of the pictures forwarded is due to a general reduction of gold on the lights as well as the shadows. Sometimes, with a toning bath in good working order, if the prints be exposed to light during the process of toning, a similar result to that sent will be produced. It is probable that you have added some salt having a reducing tendency to the gold solution ; but, of course, wo cannot tell what. The colour of gold in subdivision depends on the size of the particles, and varies from a ruby tint to purple black. The size of the particles much depends on the mode in which the gold is thrown down. Gladiator.—We can readily understand your explanation. The matter was too trivial and unimportant from the first to be worth half the attention it received. We corrected a blunder, and had no further interest in the attempts to ignore it. Your view of the matter was unquestionably sound. Wo hear from you too seldom. Electro.—Judging from the appearance of the print, we should think the cause of the want of richness in tone is due to the nega tive. With greater intensity in the negative, permitting deeper printing in the blacks without over-printing the lights, richer and deeper tones would be obtained. Probably a somewhat stronger printing bath would also help you. The lighting and general effect of the picture are good. It only lacks a little depth and rich ness. 2. Sulphocyanide of ammonium can be purchased of any photographic chemist or dealer. We do not remember its present price. OXONIENSIS.—It is very difficult to say how long a commercial sample of collodion will keep good of which we do not know the exact constitution. It is probable that if you add from half a grain to a grain per ounce of bromide of cadmium to the quantity, and put it away in a dark, cool place, that it will keep. Permanganate of Potash.—Mr. Whitfield, of Scarborough, calls our attention, and that of enquirers respecting permanganate of potash, to his announcement in our advertising pages onMarch 27. D.—Good ordinary water colours answer perfectly for tinting prints on albuminized paper. " Harmonious Colouring Applied to Photo graphs,” published by Newman, Soho Square, gives full par ticulars. Amateur.—There arc various formulae for preparing paper for en largements. That employed by Mr. Solomon for enlarging by the magnesium light gives good results. It consists of 15 grains of iodide of potassium and 5 grains of bromide of ammonium to an ounce of water, and exciting on a GO-grain silver bath containing 10 minims of acetic acid in each ounce ; develop with a saturated solution of gallic acid. You will find various articles on the sub ject in our back volumes. See, also, our Year-Book for 1865. If these particulars are insufficient, write again. Collodion.—You leave us in the dark as to your exact manipula tions in the morphine process. You remark that you follow im plicitly the instructions in our Year-Book, and then refer to an iron developer without acid, which is not recommended there. It is probably in this point that you err. The iron solution without silver has, we find, been a frequent source of failure. If you use the iron developer, add silver to it before applying it to the film. If you want a long keeping process, wo do not recommend it. It is best suited to those who wish to prepare for a few days’ work, not longer. As a rule, the conditions of long keeping involve the necessity of long exposure; and in that case wo know of nothing better than the collodio-albumen, with a final wash of gallic acid. Mr. Gordon’s modified gum process keeps well, and gives very fine results; but we have not had personal experience with it. We cannot toll the cause of the tardy development of your England’s plates. The darkness of the subject was the probable cause. In our own experience, development has been completed in a quarter of an hour. Mr. England occasionally found, with difficult sub jects and imperfect light, that the development was tardy, and in such case accelerated it by using alkaline pyro. 2. The deposit you describe was probably carbonate of silver, caused by the pre sence of a carbonate in tho water. Your letter did not contain the crystal of which you speak. We are not very familiar with the collodion you mention, but have no doubt that it is good, and that, with the addition of bromide you propose, it will answer for dry plates. 3. It is generally due to the presence of some organic impurity in the nitrate bath. Arthur Stride.—Avoid the washing in salt and water, and omit the addition of carbonate of soda to your solution of chloride of gold. This will give you a better chance of rich and deep tones. Use your fixing bath just twice the present strength. You are using it 1 part of hypo in 8 of water; it should be 1 part in 4 of water. Let us know the result. The Viper.—The subscription to the London Photographic Society is one guinea per annum and one guinea entrance. To become a member you must be proposed for election by a member. As a member you -will receive tho Society’s Journal monthly, as well as the general privileges of membership. Thomas STOTHARD.—We will make enquiry as to the formula for developing containing sulphate of zinc. Many photographers use the common crystals of nitrate of silver for every purpose, and find them answer well. J. H. (Stonehouse).— We have frequently had similar spots brought under our attention. Wo cannot with certainty state their cause, but believe them to be the result of minute air-bubbles formed on the print whilst in the fixing bath, which cause spots of imperfect fixation where they occur. G. I). Lyon.—The causes of structural markings are known by collodion makers, who generally try to avoid the defect; but it often happens in this, as in many other things, that the best results' arc obtained when the conditions are nearest to, but just avoid, certain defects. In the case to which you refer you do not state sufficiently precisely the nature of the markings. They may be due to a glutinous condition of the collodion, which renders it difficult to get an even, fine film; or it may be due to moisture, causing crapincss in the film. Coating a plate in a damp atmosphere will often produce the latter defect, even with a good collodion. If you describe more precisely the nature of the defects we can give you fuller information. John Hampden.—Wo believe tho card you enclose is tonedin an acetate bath; but quite as much depends on tho excellence of tho negative as upon the mode of toning. 2. Thore is no very simple work on tho subject. Various of the manuals contain much infor mation ; these, and our own pages, are the best guides wo can recommend you. W. F. Morgan.—Thanks. The qualities of tho pictures arc very good indeed. Your application of the process is very successful. D. Grant.—A good half-plate lens will answer for taking tho various sizes you require; but it will require a long room to produce card pictures with such a lens. Edward B. FENNESSY.—Thanks. The idea is a good one, buti has been extensively carried out already. D. J. W.—Respecting your wish expressed last wook we can give you some information if you send us an addressed envelope. E. Spencer.—The colours you mention are good for all kinds 0 photographs. 2. There is no bettor mode of making oxygen for amateurs than the usual method with chlorate of potash and man- ganeso. Other methods have been devised, but not readily applic able for amateur purposes. W. II. L.—1. The peculiarity of tho collodion becoming red and after wards colourless is not uncommon, especially when methylated other is used., It will not injure its working qualities. 2. Pure white wax may be used with advantage. By great care in usi ordinary bees’-wax, staining tho mount may be avoided. "° frequently apply it without such stains occurring. N.—We arc unable to give you tho information. Dinsdale and Co. in our next. Several Correspondents in our next. Owing to the extreme pressure on our pages, several articles, including Mr. Bovey’s continuation of the subject of Silver Printing, “Cepr right and Piracy,” “Economical Use of Artificial Light,",,"- lodio-Chloride Process,” “ Modified Transferring Process,” Hite rary Notices, and many other articles, are compelled to stand oF until our next.
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