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VOLUME XLII

CAM

The Photographic Times

FEBRUARY 1910

PHOTOGRAPHIC PROGRESS IN GREAT BRITAIN.

BY THE REV. F. C. LAMBERT.

NUMBER 2

THE LONDON SALON.

HE one exciting bit of news in London at the moment of writing is that the Photographic Salon has come to an end; at any rate, for the present. But this does not mean that the "Linked Ring" has been disbanded but rather that it is about to set its house in order and after a bit of friendly and spirited spring cleaning it will organize a new and improved version of the old Salon programme, as the hotels say, "under entirely

new management," and call the new show the "London Salon." It is a matter of common knowledge that the old lines were stale and, moreover, the time has fully come when some decided move must be made to regain the confidence of the outside photographic public. The wholesale rejection of work by the non-links which has taken place of late has choked off quite a number of those whose work heretofore has supplied the main stem of support. (More in my next, or as soon as matters have matured.)

THE LATE DR. RUSSELL.

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I am confident that all readers of this journal will join with me in expressing deep regret on hearing that death has removed from us the genial unaffected personality of Dr. W. J. Russell, F.R.S. (Professor of chemistry). From 1898 up to last year he carried out a long series of researches into the deeply interesting action of numerous substances which, in the dark, can affect an ordinary dry plate. Let me quote one experiment which I heard described by Dr. Russell some years ago, just by way of example. Take a piece of oak about the size of a quarter plate, and plane up one side as smooth as may be. If it is "figured" or dotted all the better. Now lay this down, planed side up, and lay over this an unexposed dry plate, in the dark, of course, film side down. The dry plate film and wood must not be in contact but, say, one-eighth inch

apart. This can be arranged by supporting the two opposite ends of the plate by pieces of glass, e. g., a short length of glass rod would serve excellently. The wood and light sensitive film are now left undisturbed and facing each other for some time,-I forget now whether the Doctor said twelve or twentyfour hours. The plate is then developed in the usual way, when we get a very fine image of the structure of the wood. A polished piece of coal in the same way communicates its structure to the plate. A piece of zinc on which a few scratches were made, laying bare an unoxidyzed portion, similarly gave an image. Printers' ink, but not ordinary writing ink, gives off emanations. In a word some metals, many oils, terpenes, resin, and other vegetable extracts, give off these emanations, which, Dr. Russell showed by experiment, can turn corners and also are stimulated into activity more or less by exposure to light. He came to the conclusion that the emanations are chemical rather than physical and attributed the results to the evolution of hydrogen peroxide formed by the oxidation of the active substance. We then have an explanation of how plates left in dark slides for some time show markings corresponding to the leather hinges of the shutter of the plateholder. The marking of plates that have been wrapped up in paper on which there is printing ink is a fact which is familiar to all. Plates that are kept for a long time wrapped in some kinds of brown paper, or in strawboard boxes, frequently show deterioration along the edges. Metal plateholders or film sheaths also induce markings. Other instances can be supplied by the reader's experience. It is probable that Dr. Russell's investigations indicate the cause of most of such troubles. For a long time I have been of the opinion that the best plan when touring with exposed plates is to put the plates film to film without any separating paper or anything else between them. I have observed, also, that the plates which have been wrapped first of all in waxed tissue paper keep best. I have used plates so issued after something like fifteen years keeping and found them quite good.

ARBUTH NOT'S PLATINO-GUM-BICHROMATE PROCESS.

Since my last note I have had an opportunity of seeing Mr. Arbuthnot. give a practical demonstration of his gum-platinum process, and, as this process is more or less a limited liability kind of personal procedure, it may interest. readers to have just enough information to enable them to try the process for themselves. Two points by way of preface: First, there does not appear to be any inherent difficulty, provided quite a moderate degree of care be taken; secondly, the results in Mr. Arbuthnot's hands are quite remarkable and forceful.

In brief, the process consists in making an ordinary platinotype print, coating this with gum-bichromate mixture, giving a second printing, and developing the gum print in the ordinary way. Starting then with an ordinary black and white platinotype print, developed, cleaned, washed, and dried in the ordinary way, our first business is to size the print to prevent the gum bichromate coating from sinking in too much. A solution of ten to fifteen grains of Heinrich's hard gelatine per ounce of water is made, first by soaking the gelatine in

cold water and then warming it in a water-bath to about 120 degs. Fahr., stirring thoroughly, and allowing it to cool down to 70 degs. Fahr. The print is laid on clean blotting paper and pinned to a drawing board and the gelatine solution brushed over its surface with a soft brush and worked up into a frothy coating. This is now removed by lightly wiping the frothy part with a handful of clean dry muslin, leaving the paper coated with a layer of gelatine. A second coating of size may be required with any brand of thick or extra absorbent paper, but this is not applied until the first coating is quite dry. The printing mixture is prepared by dissolving two ounces of clear gum arabic in five ounces of water, to which one or two drops of carbolic acid may be added if the gum solution is not being used right away. Prepare also a saturated solution of ammonium bichromate. Procure some moist water colors in tubes, as used by artists, squeeze out into a cup one-quarter inch of such pigment, say lampblack, add half ounce of the gum solution and half ounce of the bichromate solution and mix very thoroughly. Pin out the print over a sheet of blotting paper on the drawing board as before. Then brush over the print a coat of the gum-pigment mixture with a flat bear's hair brush and even it out with a badger softener, just as with ordinary gum bichromate printing. Dry the paper, print and develop it in the usual way. Registration can most easily be secured by using a piece of paper just a trifle larger than the negative, fixing this to a board by means of pins along the edges of the paper and laying the negative on the paper and board and pushing the negative close up to two pins along one side and two along an adjacent side. By means of these pinholes in the paper the negative can be accurately replaced time after time for two or more printings.

Now what is the object of all this? In a word it is designed to modify the scale of tones given by the first (platinum) print. Suppose this gives a print weak in the lighter tones. In such a case we use one-eighth to one-quarter inch of pigment in the above mixture. This gives a light colored coating. Printing is carried fairly far and the lighter tones as well as all other parts are strengthened. Again suppose the shadows of the platinum print are not full enough. In such case we use one-quarter to one-half inch and get a more opaque coating. Printing is somewhat short. This tends to enrich the shadows with little or no addition to the lighter tones. Roughly put the printing speed of the above mixture is about equal to ordinary P. O. P., so that a strip of that paper will serve as an actinometer. Should the printing of the gum coating be found unsatisfactory, it can be removed by soaking the print long enough in a strong solution of alum. Curiously enough, this alum solution at first seems to have a hardening effect on the gum, but after a while it appears to disintegrate it so that it can be easily removed with a soft brush.

LENS ARITHMETIC.

Many of the rules and formulas set out for photographers are needlessly. complex. One of the commonest questions that comes my way, month by month, is the request for a very simple rule-to find the distances between the

lens, negative, and enlargement. Instead of giving a verbal rule let us consider a simple case. We can then word the rule for ourselves.

Suppose the lens has a focal length of six inches and that we wish to enlarge a quarter plate, 4 x 3, negative on to a 12 x 10 piece of paper. This means a threefold enlarging of each side of the negative, giving us a 12x9 print. Call this number three, the ratio. Clearly the distance between the lens and paper will be longer than that between the lens and negative.

Longer conjugate (Lens to paper): Multiply the focal length 6 by 3, getting 18, and add one focal length 6, getting a total of 24.

Shorter conjugate (Lens to negative): Divide the focal length 6 by the ratio 3, getting 2, and add one focal length 6, getting a total of 8. Now as a check to our arithmetic we should always notice that the two conjugates should also bear the same proportion, 24 to 8, as the ratio number, viz., 3.

To make matters clear, let us take one more example. This time we wish to reduce a 72 x 5 negative to make a lantern slide, where the longer side of the reduced picture is 3 inches; that is to say, 71⁄2 has to be reduced to 3. Putting this in half inches it is reducing 15 to 6 or ratio 15/6. Now in this case the longer conjugate will be between the lens and negative.

Longer Conjugate: 15 times focal length 6 gives us 15, and adding 6 we get 21.

6

6

Shorter Conjugate: 6 divided by is 6 multiplied by or for 21%. Adding 6 we get 8. To check our working we must compare 21 and 8. or 21 and 12. The larger ought to be 5 times the smaller. So if we multiply 18 by 15 we ought to get 21, and this is easily seen to be the

15

15

126
15

case.

There is one other common trouble with lenses,-viz.: the f value of stops when the lens is being used for near objects, such as copying, etc. Now we may for all practical purposes consider that the f value of a stop is found by dividing the distance between the stop and the focusing screen by the diameter of the stop. Suppose the diameter of the stop to be one inch and the lens-toplate distance is eight inches. No matter what the focal length of the lens, then, in such a case this stop is practically working at f8. But suppose we do not know the diameter of the stop opening, and only its engraved value,-what then? For instance, suppose the lens has a focal length of 5 inches and a certain stop is marked f8, but the lens is for the moment working at 9 inches between the stop and plate. This stop has a diameter of one-eighth part of 5 inches, it bears, therefore, a smaller relation to 9 inches, or has a higher f number, and the change will be as 5 is to 9. So, then, a simple rule of three tells us that as 5 is to 9 so is 8 to the new stop value, i. e., 8 multiplied by 9 and divided by 5 is between f14 and f15. Lastly, what about exposures, for as a rule we are more concerned with comparative exposures than with stop numbers? For the same actual stop the exposures increase as the square of the distance between stop and plate. That is to say, equivalent exposures with the same stop vary as 5 times 5 (25) and 9 times 9 (81), or the second exposure will be roughly 34 times the former.

FIGURE COMPOSITION.

BY SIDNEY ALLAN.

One-Figure Composition.-Difference Between Portraiture and Pictorialism.Suitable Subjects.-Values.-The Connecting Link.-Texture.-On the Rendering of Flesh Values.-With Thirteen Illustrations and Four Diagrams.

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CHAPTER X.

'N DISCUSSING one-figure composition which will furnish the main topic of this paper, I do not intend to dwell upon portraiture, but I would like to make clear the difference between a portrait and a pictorial figure.

Portraiture is a specialty. An accurate likeness and a characteristic pose are the main objects. The whole interest is concentrated upon the face, and every other consideration is sacrificed to it. A portrait is rarely a pictorial masterpiece, and

a pictorial representation is hardly ever a good portrait.

In pictorial composition there is no limitation. The aim is to produce something beautiful and not a record. The human figure can be used to express the whole gamut of human emotion and shown in every attitude and action that is pleasant to contemplate.

Of course, one-figure composition is somewhat limited in expression for pictorial purposes. A striking pose is often deemed sufficient. You may ask how does it then differ from portraiture. Well, let us look at the "Spanish Dancer" by Robert Henri (Fig. 113) and Chas. W. Hawthorne's "Man with Oar," Fig. 112. Nothing simpler could be imagined. Each depicts an interesting type in a natural pose. And yet nobody would consider them portraits. Why? The answer in most cases would be, there is something about them that one does not associate with portraiture, something more picturesque, more free and spontaneous. They were not made for the face alone, but treated in a broader manner, to present a type of humanity without subterfuge, merely to please the artist. And for that reason we find a stronger emphasis of line, a more unconventional pose, a finer handling of detail. What portraitist would venture to represent an arm like that of the dancer, or introduce a big white spot like the pan of the fisherman in the lower part of an upright. Portraitists are perhaps too much the slaves of the public, but even the best can not overcome certain restrictions; they have to be matter of fact and can not allow themselves many flourishes for mere beauty's sake. One-figure composition is perhaps most suitable to simple depictions of types like figures 69, 71, 83, 84, 89, 112, 113, etc., that are interesting in themselves and do nothing in particular. Costume studies do not fare quite as well. One expects some explanation, some meaning. Fig. 70 is called

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