The photographic news

• Bandzählung: 6.1862
• Erscheinungsdatum: 1862
• 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-id1780948042-186200003
• PURL: http://digital.slub-dresden.de/id1780948042-18620000
• OAI: oai:de:slub-dresden:db:id-1780948042-18620000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Bemerkung: Seite 1-72 fehlen in der Vorlage. Vorlagebedingter Textverlust.
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

[September 19, 1862. 454 THE PHOTOGRAPHIC NEWS. Septi PRINTING DIFFICULTIES. Sir,—Having in my last letter endeavoured to prove that the presence of free nitrate of silver on the surface of the paper causes mealiness, I shall now briefly consider the con ditions which qualify it to act. Strictly speaking, this salt is insensible to the photogenic action of sunlight; yet, strange to say, from experiments made, I find its presence is absolutely necessary to produce a satisfactory image on the surface of the paper; this fact, at first sight, would appear an unfathomable paradox, but a little consideration enables us to see through the matter more clearly. The fact of our being able to remove by washing all traces of free nitrate from the paper before its ex posure proves that up to that time it exists in an independent and inert condition ; but wheif brought into contact with actinic light, immediately a portion of the salt enters into a combination which no amount of washing can remove. Several months since, whilst studying the singular pro perties of light, I imbibed the idea that what we are accus tomed to term actinism is nothing more than an electrical action ; that idea recent research bids fair to prove correct. Now, sir, I believe the combination spoken of to be effected by electric influences, the two salts (chloride and nitrate of silver) being necessary to produce the action and reaction which ultimately change their character, and they are united into one, thus forming the coloured substance which 8, to 9qasa 80; 11o ar Kt" Be 53 2 vi 25 the mo: adding t his tinge brought becomes compani back up itself, an my opin being re them, an peated st Hen, if a fe more tonsider: nay, per albumin: n giving healbur Brface ol De remov klan 0g expei fended *'4 you, Bent to t M by ^Usetl 6old to w "as addei Mmeal j 5 pione Sited S dha ' I,these n Sy Snue ■ proposed. Whilst recently discussing the matter with a friend, he placed in my hand a copy of your “ Liverpool Contemporary,” containing “ A Chat about Glass Houses ” by Mr. A. II. Wall, in which he gives a diagram, similar to that you gave some months ago, of the glass house of Mr. Fitch, without side light at all, of which he speaks very highly. He also strongly recommends the use of a front light upon the sitter, and quotes examples in confirmation of his opinion. Now, sir, notwithstanding the vagueness of which I have complained amongst other writers, I have found them all agreed in two things, namely, the importance of avoiding a front light, and in the value of a proper amount of side light. Mr. Wall says he is the first to recommend a front light; but I am sorry he does not give his reasons for the recom mendation. He says it serves “ to secure roundnessbut that is just what all other writers have stated it does not do; flatness being regarded as its general result. Will you be so good, then, as oblige me with answers to the following questions:— 1. Is a northern aspect absolutely best, and why ? 2. Is there sufficient advantage in the use of white glass over green to justify the extra cost ? 3. Is a side light absolutely necessary, and why ? Is top light absolutely necessary, and why ? 4. Do you think, from the authorities Mr. Wall quotes, or his own opinion, that a front light is desirable? 5. Do you approve of Mr. Sutton’s plan of a glass house, given in his Notes, September 15, 1801 ? As I wish to get the best house I can with the least trouble and expense, I shall be glad to receive an early answer in your columns.—Your obliged reader, H. G. B. Kensington, September 2nd, 1862. [The vagueness, of which you complain, doubtless arises from the impossibility of laying down absolute rules for application in varying circumstances. It generally happens that glass houses have to be built to suit the exigencies of the position, not as the photographer would choose, but as he can, and individual judgment must generally be used to meet each case. We have not space here to enter into the subject at large, but will answer your questions categorically. 1. A northern aspect is, undoubtedly, best, and for many reasons. It is generally a pure, steady light, casting no direct, abrupt shadows, and, unlike the south or other quarter from which the sun directly shines on to the sitter, it is not subject to troublesome fluctuations from passing clouds, rendering perpetual variation in the time of expo sure necessary. gives stability to the picture. The beautiful laws which govern atomic combinations teach us that these chemical changes are not under the pre carious government of chance. Atoms unite with atoms m regular undeviating proportions, which go to prove, in the case now under notice, that when the chloride of silver a paper contains has combined with its chemical allowance 0 free nitrate, be the sensitizing bath strong or weak, not one atom more will it exercise an influence on; what remans must exist as a free salt, or it must seek a connection fSr where. But another difficulty here presents itself, Whicpre left unanswered, must upset all my former arguments. . ITt nitrate of silver, I repeat, is not affected by light; true, 2. A great deal of actinic light is, unquestionably, stopped out by green glass; but it unfortunately happens, that white glass is apt to turn yellow by exposure ; it is doubtful, therefore, whether the advantage gained by its use is commensurate with its cost; especially, as in building a house, you can have more glass to compensate for the loss by colour. 3. A side light is most important to good results : a por trait taken with direct vertical light is generally far from pleasing. Wherever it is possible, the room should have glass in the sides; but where it is impossible, then the room should be large enough to make the light from the top virtually a side light. In the room of Mr. J. R. Williams, referred to, he is enabled from its large size, and by closing completely some of the many blinds at the top, over the head of the sitter, to allow the light to fall on the sitter much in the same way as if it were from a lofty side light. A top light is not absolutely necessary ; but if it be absent, the side light should be veryelofty to compensate. You require, in truth, facilities for allowing the light to fall upon the sitter at about an angle of 45°, more or less, as the character of the model may require, and it is immaterial whether the light enters at the roof or sides, if the proper angles be secured. For card portraits a greater proportion of direct side-light is required than for large heads. 4. All the light which falls on the sitter should be, in a certain sense, front light: that is, it should fall from variot: parts in front of the sitter. If, by front light, you mean, window in front of the sitter, we decidedly disapprove of it. All the top light, and much of the side light, may be front, and if there be a window in front, but 8 or 10 feet from the ground, that is permissible. But all light striking the sitter at an angle with the floor of, say, less than 25 or 30°, we should regard as injurious, giving a flat effect to the face, and most disastrous to the expression of the eyes. It is always desirable that the sitter look into darkness, if possible, not simply because it is easier and aids in pro ducing a better expression, but because the pupil will be more dilated, and will, in the photograph, look darker and brighter. With light directly in front of the eye, on the other hand, the pupil contracts, and the eyes look small, light, and poor. 'The front light in the glass-houses of Mr. Window and Mr. Fry, is there from the necessity of the position, not as a matter of choice. In Mr. Window’s it is of dark blue glass; and in both of them, it is not only a consider able distance from the model, but the model is always placed in such a position with regard to it, that it becomes, practi cally, a side light. 5. We consider Mr. Sutton's plan the best, in principle, that we have seen proposed. The objection we made to it was, simply, that in the proportions given the light admitted would be insufficient for use in large towns. The late Mr. Lacy, who had the most clear and precise views on lighting the model, of any photographer with whom we have met, stated to us, that if he had another glass-house to erect he would build it upon this principle, slightly modified. We regret that, by his untimely end, our readers lost some papers on the principles and practice of lighting, of which he had just commenced the preparation.—Ed.]