Suche löschen...
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
- Lizenz-/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
- Fotografie
- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Bandzählung
- No. 1699, March 27, 1891
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Ausgabe
- Parlamentsperiode
- -
- Wahlperiode
- -
-
Zeitschrift
The photographic news
-
Band
Band 35.1891
-
- Ausgabe Ausgabe 1
- Ausgabe Ausgabe 17
- Ausgabe Ausgabe 37
- Ausgabe Ausgabe 57
- Ausgabe Ausgabe 77
- Ausgabe Ausgabe 97
- Ausgabe Ausgabe 117
- Ausgabe Ausgabe 137
- Ausgabe Ausgabe 157
- Ausgabe Ausgabe 177
- Ausgabe Ausgabe 197
- Ausgabe Ausgabe 217
- Ausgabe Ausgabe 237
- Ausgabe Ausgabe 257
- Ausgabe Ausgabe 277
- Ausgabe Ausgabe -
- Ausgabe Ausgabe 313
- Ausgabe Ausgabe 329
- Ausgabe Ausgabe 345
- Ausgabe Ausgabe 361
- Ausgabe Ausgabe 377
- Ausgabe Ausgabe 393
- Ausgabe Ausgabe 409
- Ausgabe Ausgabe 425
- Ausgabe Ausgabe 441
- Ausgabe Ausgabe 457
- Ausgabe Ausgabe 473
- Ausgabe Ausgabe 489
- Ausgabe Ausgabe 505
- Ausgabe Ausgabe 521
- Ausgabe Ausgabe 537
- Ausgabe Ausgabe 553
- Ausgabe Ausgabe 569
- Ausgabe Ausgabe 585
- Ausgabe Ausgabe 601
- Ausgabe Ausgabe 617
- Ausgabe Ausgabe 633
- Ausgabe Ausgabe 649
- Ausgabe Ausgabe 665
- Ausgabe Ausgabe 681
- Ausgabe Ausgabe 697
- Ausgabe Ausgabe 713
- Ausgabe Ausgabe 729
- Ausgabe Ausgabe 745
- Ausgabe Ausgabe 761
- Ausgabe Ausgabe 777
- Ausgabe Ausgabe 793
- Ausgabe Ausgabe 809
- Ausgabe Ausgabe 825
- Ausgabe Ausgabe 841
- Ausgabe Ausgabe 857
- Ausgabe Ausgabe 873
-
Band
Band 35.1891
-
- Titel
- The photographic news
- Autor
- Links
- Downloads
- Einzelseite als Bild herunterladen (JPG)
-
Volltext Seite (XML)
March 27, 1891.] THE PHOTOGRAPHIC NEWS. 245 THE NEW HELIOCHROMIC DISCOVERIES* BY LEON VIDAL, EDITOR OF “LE MONITEUR DE LA PHOTO- GRAPHIE," PARIS. Recently considerable attention has been given to the communication of Professor Lippman to the Academy of Sciences in relation to the photography of colours. It may be interesting to the readers of Wilson's Photographic Magazine to be posted in regard to this discovery, and to have these details from an eye-witness of the results obtained. For this reason I dedicate to them this explan atory note made just after an interview with Professor Lippmann himself. He was good enough, in his laboratory at the Sorbonne, to show me his results, his appliances, and to explain thoroughly his method. The prints of the spectrum which he showed me have, for the most part, a brilliancy which has never been possessed by the colours of the spectrum reproduced by other methods (processes of Becquerel, &c.). In fact there is colour, brilliant colour. M. Lippmann’s experiments are based on interferences, consequently he acts with the aid of a sensitive film resting on a reflecting surface. The incident rays pass through the film until meeting with a metallic surface (this is mercury) ; they are then reflected and again pass through the sensitive film. From this meeting of the incident rays and the reflected rays is produced what is called interfer ence. There is formed in the body itself of the sensitive film a succession of maxima corresponding to the phases of light, and of minima corresponding to the phases of obscurity. The length of a luminous ray is but a very small portion of a millimetre, and, admitting that the thick ness of the film is one-twentieth of a millimetre, there is produced in this thickness considerable quantities, giving, on an average, from 150 to 200 white and black rays, and resulting from the development after the action of the light. This development blackens all the zones in which the maxima have been produced, whilst in the zones of the minima, obscurity having reigned, there has been no photographic action, and consequently the sensitive film remains unchanged. It follows that after development and fixing in the ordinary manner, we have a film divided into an infinity of black parallel lamin, separated from each other by white spaces, and the inter vals have exactly the length of the wave characterising each colour. In the present case we only refer to the spectrum, either for the primary colours isolated from each other, or mixed in definite relations. If it were possible to cut through the film, and to count the lamina; in the portions corresponding to each of the seven colours, we would find unequal quantities of lamin®, and especially unequal distances between each lamina for each of the colours. But in reality no colour would exist, except the network having the faculty of causing the light to produce for the eye the sensation of colour. There would be no more colour than in soap-bubbles, although these appear to us most richly coloured. The phenome non is also produced with lamina? of mica, so that, according to the thickness of these laminae, we have any desired colour of the spectrum, although the mica lamina is absolutely colourless. The analogy is striking between the results obtained by Professor Lippmann, and the examples given above. In order to obtain them he covers a glass plate with a coating, * Abridged fiom Jfihon's Photographic Magazine, Philadelphia, March 7th, serving as a vehicle for a sensitive silver salt, but in such a manner that the film is continuous, and free from granu lations. He applies the sensitive film direct to a mercury bath, and he causes the image of the spectrum to fall on the sensitive film through the glass. The exposure lasts from about one to two hours. Development and fixing as usual. With orthochromatic plates sensitive to the red, especially, the time of exposure would be much reduced. This method is somewhat analogous to that of storing sonorous vibrations in the phonograph. The sensitive film stores away luminous vibrations which will show themselves as soon as the surface comes in contact with the luminous rays. We may say with reason, there fore, that the colours are permanent, as they cannot disappear unless the physical condition of the film is modified to the point of destroying the lamin® by crushing them. It is not possible yet to draw any practical conclusions from the interesting facts which have just been explained, but there must be a beginning to all things, and we find ourselves here in the presence of the most rational starting point, one the most likely to lead to the true solution of the difficult problem of the representation of the colours. There are, however, two serious objections to oppose to the easy practical use of this ingenious and seductive process. The first is based on the unequal sensitiveness of the plates for the different colours ; the second, because the interferences are only produced in a regular manner with pure colours. In this case the maxima and minima are equidistant for rays having a given length of wave; but if the colours are complex or mixed with white light, the equidistance yields to some period from which results an irregularity in the arrangement of the films of reduced silver, which no longer give the sensation of the complex colour which has produced this particular dis position. It is this last objection, especially, which seems to us the most serious. We shall have to wait new expe riments on mixed colours in order to exactly ascertain if the corresponding vibrations are produced in the midst of the profusion of waves of all lengths. We cannot yet say that this will not be, but it will be necessary to verify this discovery by experiment before being able to affirm its truth. He : “ Do you think the photograph I mailed you the other day was like me ? ” She : “ I hope not ; when it came it was broke. ” GROTESQUE PHOTOGRAPES.—It happens to all amateurs, and, alas ! to professional photographers, to have failures in making their negatives. We think to please them by indicating a means of utilising what, in any less noble art than photography, we would designate as “botches.” Here is the method I— Take the sacrificed negative—a portrait, for example—and, if dry, soak it for a moment in water ; then expose it, the gela tine film on top, to a source of heat—in the sun, for example. The gelatine melting under the action of the heat makes it slide skilfully in any direction of the negative by giving it the proper inclination. You will now see the nose of the patient become longer or shorter at the will of the operator, and the rest of the face will take on very strange expressions. A prac tised hand will change a profile into a crescent, and a full face into a full moon. This artistic operation properly done, dry the negative and print in the ordinary manner. As is seen, the operation is ridiculously simple, and the result positively hideous. We will offer, however, a last recommendation to our readers. Before operating, make sure that you can obtain the assistance of two friends as seconds, in case the subject should happen to see your work.— DIAFRAGNIK, in Photo, Gazette,
- Aktuelle Seite (TXT)
- METS Datei (XML)
- IIIF Manifest (JSON)