Photographic Amusements Part 6

A curious experiment showing that a photographic dry-plate can be otherwise affected than by light, so as to form an image upon it, is the following:

An image of copper in relief is necessary--a penny will do for this purpose. Place an unexposed dry-plate in a normal pyro developer, and on it lay the copper coin. After about five minutes or so, remove the penny, fix and wash the plate, when a perfect image of the penny will be found on it.

ELECTRIC PHOTOGRAPHS.

Similar experiments to that described above have been carried out by Prof. Fernando Sanford. He placed a coin on a dry-plate and connected it with the terminal of a small induction coil, capable of giving a spark of three or four millimeters, while a piece of tin foil upon the opposite side of the plate was connected with the other terminal of the coil.

Several negatives were made in this way, the accompanying photograph, Fig. 58, being from one of them. With one exception, they all show a fringe around them, due to the escape of the charge from the edge of the coin, which accounts for the formation of the dark ring observed around the breath figures made upon gla.s.s.

Later on he undertook to photograph in the same way objects insulated from the photographic plate, and has since made negatives of coins separated from the plate by paraffine, sh.e.l.lac, mica, and gutta percha. The accompanying photograph, Fig. 59, was made with the coin insulated from the photographic plate by a sheet of mica about 0.04 mm. thick. The mica was laid directly upon the film side of the plate, and the coin was placed upon it and connected to one terminal of the small induction coil already mentioned. A circular piece of tin foil of the circ.u.mference of the coin was placed upon the gla.s.s side of the plate directly opposite the coin, and was connected to the other terminal of the induction coil. The little condenser thus made was clamped between two boards, and was covered up in a dark room. Two small discharging k.n.o.bs were also attached to the terminals of the induction coil, and were separated by a s.p.a.ce of less than a millimeter, so that, when a single cell was connected with the primary coil, the spark between the k.n.o.bs seemed continuous.

[Ill.u.s.tration: FIG. 58.]

[Ill.u.s.tration: FIG. 59.]

The plate was exposed to the action of the waves set up in this condenser for one hour, when it was taken out and the negative image developed upon it by the usual process.

MAGIC VIGNETTES.

These are reversed vignettes, that is to say, the margins round the portrait instead of being white as in the ordinary vignette are black.

A method of making them was recently described by "Teinte" in _The Photogram_. This was as follows:

Two methods can be adopted. The first of these about to be detailed, though entailing, perhaps, in the first place a trifle more trouble, produces the best results. We require a black background, preferably of black velveteen, large enough for a head and shoulders. As the material is not usually obtainable of a width greater than twenty inches or so, there will have to be a seam, and this must be very neatly done. The seamed velveteen is then stretched taut on a frame, which should preferably be covered first with calico, to prevent "sagging." Always, before use, dust the velveteen with a soft brush--say, a hat brush--to remove any adhering dust or fluff. Instead of velveteen, a good paper background can be used, only it must be seen that the surface is smooth and free from cracks or creases, and is _dead black_.

[Ill.u.s.tration: FIG. 60.--MAGIC VIGNETTER.]

We require also a vignetting mask suitable to the subject, with a serrated edge. This has to be fixed inside the camera between the lens and plate.[4] The proper position can be found by trial; the further the card is away from the plate the softer and more gradual the vignetting. No special arrangement for holding this is required beyond what can be prepared by any one who can use his fingers. We take a piece of stout card, the outside of which will just fit into the folds of the camera's bellows, and by a little twisting it can be sprung in between the folds which will hold it. There is an opening in the center, square in shape, about quarter plate size. This acts as a frame to hold the vignetting mask, which has the opening of proper size and shape. By using a frame as described the vignetter can be moved about up and down and from side to side, and when the correct position is found fixed by drawing pins. The frame and vignetter should be blacked all over. For this purpose take some lampblack ground in turps, and mix with it a little gold size sufficient (found by trial) to prevent the lampblack from rubbing off when dry, but not enough to cause the paint to dry shiny.

[4] A vignetter for the purpose, as shown in Fig. 60, has been placed on the market.

A good distance to fix the vignetter is about one-third the extension of the camera when the object is in focus, measuring from the lens.

We adjust the camera so that the image of the figure falls in the correct position on the screen, and the vignette is made of such a size and shape as to give the amount required.

The shadow of the mask protects the edges of the plate surrounding the image, and in development we obtain a negative in which the image is vignetted into clear gla.s.s, and on printing from such the margins print dark. The printing of such a negative should be prolonged until the margins of the picture are quite lost, or they are apt to show after toning.

The sketch shows the arrangement of vignetter inside camera.

The other plan consists in making an ordinary negative, using preferably a dark background. From this is made a vignette in the ordinary manner. When this comes from the frame it is placed on a piece of clean gla.s.s--face up--and another piece of gla.s.s free from flaws placed over it. Now cut a piece of card to the size and shape of the vignetted portion of the print, and fix this with glue to a piece of cork. This piece of cork must vary in thickness with various pictures. Now place the cork on the gla.s.s so that the mask covers the picture and fix with glue to prevent slipping. Place the whole out in diffused light, and allow the darkening of the margins to go on until sufficiently deep. The print is then toned.

The height of the card from the print must be such that no abrupt line is produced between the first printing and the darkened margin, but that one will shade into the other without break.

A SIMPLE METHOD OF ENLARGING.

If we have an ordinary gelatine negative, say, of half-plate size, and require to enlarge it to a whole plate, the simplest plan is to thoroughly wash it and immerse in a solution composed of citric acid, 2 ounces; hydrofluoric acid, 1 ounce; acetic acid (glacial), 1 ounce; glycerine, 1/2 ounce; water, 20 ounces. The action of the hydrofluoric acid will be to detach the film from the gla.s.s, while the other acids will cause the film to spread out considerably; the action being even all over, the image is completely enlarged. It is then carefully removed and washed in plenty of clean water, after which it can be transferred to a larger piece of gla.s.s. The action is sometimes to weaken the negative in density; it is therefore occasionally necessary to intensify it.

MOONLIGHT EFFECTS.

Curious as it sounds, very good moonlight effects can be procured on a bright sunshiny day. A photograph is made of a landscape in dazzling sunlight, a small stop and rapid exposure being given. The plate should, if possible, be backed with any of the substances recommended to prevent halation. Choose a landscape, with the reflection of the sun's rays in water, and include this and the sun itself on the plate.

It is best to wait, however, until the sun just disappears behind a cloud. Shade the lens so that the rays do not shine on it direct, and expose rapidly. Use an old or weak developer. The sun and its reflection will, of course, make their appearance first. Continue the development until the detail in the under-exposed parts is just visible, and fix. Print very darkly, and slightly over tone. If printing is done upon green developing paper, and a little re-touching with Chinese white, the effect is very good.

[Ill.u.s.tration: Photographed from Nature by Fred. Graf. FIG.

61.--MOONLIGHT PHOTOGRAPH.]

PHOTOGRAPHING SNOW AND ICE CRYSTALS.

There are few photographers who appear to be aware of the many beautiful phenomena of nature that can be studied by the aid of photography. Under the t.i.tle of "Schnee Crystalle," Dr. G. h.e.l.lmann has published[5] a book on this subject profusely ill.u.s.trated with engravings and photo-micrographic collotypes from direct photographs by Dr. R. Neuhaus.

[5] Rudolph Muckenberger, Berlin.

[Ill.u.s.tration: FIG. 62.--SNOW CRYSTALS. PHOTO BY DR. NEUHAUS.]

Dr. Neuhaus describes his method of photographing snowflakes in Dr.

Eder's Jarbuch, from which article we extract the most important and interesting paragraphs: Were we to attempt to photograph snow crystals in a perfectly cold room, the temperature is still higher than that out of doors; moisture at once precipitates upon the carrier of the object; the crystals would melt and evaporate after a short time. The work must be done in the open, and perfect success can be expected only when the temperature is near zero.

[Ill.u.s.tration: FIG. 63.--SNOW CRYSTALS. PHOTO BY DR. NEUHAUS.]

Snow crystals evaporate rapidly even in low temperature, and the work requires to be done rapidly and with caution. Freshly fallen snow only will give a good photograph, and as we are compelled to work in the midst of the snow storm, the task becomes still more complicated and difficult. Snow crystals but a short time after falling break, the broken pieces freeze together and crystallization is destroyed. For the illumination of snow crystals, transmitted light only can be used; reflected light destroys the shadows, and injures the high lights, and the result is necessarily but a very imperfect picture of the object.

[Ill.u.s.tration: Photo by Martin. FIG. 64.--A NATURAL PHENOMENON IN ICE.]

Diffused light, especially that of a dark winter's day, and during a snow storm, is not fit for this kind of photo-micrographic work, and we must resort to artificial light, preferably to that of a petroleum lamp. To prevent heat action emanating from the illuminating ray cone, an absorptive cell of alum solution should be interposed. As alum solution freezes at about 20 Fahr., chloride of sodium is added. With Hartnark's projection system, at 31 mm. focus distance, from 5 to 7 seconds upon an erythrosine plate is ample.

[Ill.u.s.tration: FIG. 65.--PHOTOGRAPH OF FROST CRYSTALS. BY JAS.

LEADBEATER.]

Dr. Neuhaus has made photographs of more than 60 different ice and snow specimens. The pictures of ice crystals much resemble those of h.o.a.r frost, deposited after a cold winter's night. Of snow crystals, the doublets are highly interesting, two crystals merged into one, and those having pa.s.sed through a moist stratum of air, when microscopic drops of water will freeze into the hexagonal form, giving the picture an appearance very much resembling cauliflower.