Tuesday, May 20, 2008

EX CATHEDRA: Ghost Images or Flare, Camera Copies and The Shop Window.

Ghost Images or Flare

It is a known fact that many of the finest pre-war anastigmats frequently give both ghost images and flare when dealing with subjects which throw a strong light into their glasses. The defect is much lees often met when single lenses or the single components of convertible auastigtmats or R.R. instruments are employed. "Ghost images" or "flare'' are regarded by many photographers as being the more likely with instruments having many glass-to-air surfaces, and as a matter of fact, though not as a general rule, the more of these surfaces there are in the instrument the more likely is the defect to be in evidence in certain classes of work. It is not realized as well as it might lie by those who possess anastigmats which exhibit flare or ghost images that much may be done to assist in eliminating these if the instrument is provided with a sufficiently deep hood. We have in our own possession an anastigmat with no less than ten glass-to-air surfaces, and invariably when this lens is used against the light or under like conditions the defects are sure to manifest themselves, yet when the front glass is shaded with a deep and efficient hood we have never had the least reason for complaint. The rarity of ghost images or flare when R.R. or single lenses are used may be traced in part to the fact that with the former class the hoods are much more efficient: as regards the latter, when the single components of the convertible anastigmat are employed it is nearly always the front lens that is removed, and thus the mount of the lens serves as a highly efficient hood for the back glass.

Camera Copies.

The recent installation of the Photostat Patent Office brings forward the subject of quick and cheap copying of documents, printed matter, or drawings, by means of the camera. As most of our readers are aware in this and similar apparatus, the print is made by exposing bromide paper in a special camera which is scaled to various sizes. The image is normally a negative one, although positives may be made by recopying them same size. Taken in an ordinary camera the images would be laterally inverted, but this can be obviated by fitting a reversing prism or mirror to the lens, the latter being, of course, much the cheaper arrangement. We think that photographers who work for engineering and other manufacturing firms would do well to take this class of work into consideration, as it would secure many orders for copies of drawings, plans, etc., not amenable to duplication by the usual heliographic methods, which call for a translucent original. It should not be difficult to arrange an attachment to any ordinary large camera for moderate-sized subjects, while larger ones could be managed by taking a small negative and enlarging in the usual way. We have seen some excellent copies up to three feet across made in this way and as the work practically mechanical, highly-skilled labour is not necessary. On point is essential, and that is that the same lens should be used both for making the negative and the enlargement. The operation has been very successfully carried out thus: supposing an architect's drawing has to be reproduced, a copy is made upon a process-plate, say, half-plate or whole-plate size, the distances between lens and original and lens and plate being accurately measured. The lens is then transferred to the enlarger, and the negative and bromide paper carefully placed at exactly the same distances, the result being a full-sized copy free from any distortion, the image having been made to travel back through the same optical system by which it was produced. Where much work has to be done it would be well to have both camera and enlarger rigidly set to the required points so that for full-sized reproductions no setting would be necessary. With a proper artificial lighting scheme the exposures of both plate and enlargement would be a fixed quantity, and a spoiled sheet almost unknown.

The Shop Window.

A few days ago we were asked whether it was advisable to retain a shop window for the display of specimens or to be satisfied with show-cases in a lobby and let off the shop. This is not quite such a simple question to answer as it appears at first sight, since many factors have to be taken into consideration. The first of these is the class of business which is intended to be done. The highest class of portraitists depends almost entirely upon introductions and to a lesser degree upon reproductions of their pictures in the press. Some go no farther than a brass door-plate to advertise their locale, a few even dispense with this, while others have modest show-cases with only one or two specimens on view at a tine. A few of the older firms have large lobby shows or shop windows, but it is not until we reach those who cater mainly for chance trade that we find the window show really popular. Recently there has been a great increase in these window shows in London and other large centres, so that we must conclude that they have been found to be a paying proposition. It may be noted that many of the large portrait shops are being run by people who are also engaged in other branches of industry, and they have treated photographs in the same way as they would clothes, jewelers, or tobacco. Surely, therefore, it is quite in order for the photographer, pure and simple, to take a leaf from the business man's book and to go in for bold advertisement, providing that he has the means to do it properly, and not to lose sight of the next important factor in the matter that of locality. To be effective a window display must be situated where there is a considerable amount of traffic, and in what may be called a shopping or market thoroughfare, where there are other attractions. Even in the same street one position is valuable and another almost worthless. In nearly every important thoroughfare there is one side which is much better for business than the other, and this keen business man is careful to ascertain before he invests his money.

Photography's War Work

[The immense part played by aerial photography in the prosecution of the war is naturally realized by photographers, a very large number of whom have been practically engaged in carrying it on. But perhaps the magnitude of the scale is not a matter of common knowledge, and therefore we embrace the opportunity of reprinting from the "Daily Telegraph" of Monday last an article which presumably embodies official figures. It is interesting to find that in the essential matters of cameras and lenses the British forces were better equipped than the German. The fact has recently been the subject of remark as regards lenses, and the writer of the 2 notes printed below describes, it will be noticed, the same superiority in respect to cameras. Eds. "B. J."]

           When hostilities broke out in 1914 aerial photography was still in its primitive and experimental stage. A considerable amount of pioneer work had been done both from balloons and aero planes; a small but valuable literature was arising; but the impetus of war was required, with the aid of the immense scientific and technical resources behind the Royal Air Force, to exploit its possibilities. Some idea of the progress made can be gained from the fact that on the Western front alone during the last ten months of war no tower than 264,605 Royal Air Force negatives were taken in the air over German territory, and the gigantic total of 5,800,000 prints was made from these negatives for the use of the Intelligence Staff.
           The most recent types of Royal Air Force cameras are very highly finished pieces of work. .The lens itself is shielded in a deep tube which faces vertically downwards, thus preventing direct sunlight falling upon it. At the other end of the camera is a steel chamber, containing the automatic device for changing the plates after each exposure. The entire apparatus is securely fastened to the side of the machine, and u connected by a wire with the observer's seat. The pressure of a lever is sufficient to expose a plate and to bring a new plate into position. The German cameras, as recently exhibited in the Strand, lack many of the exquisite mechanical refinements of the British instrument, particularly the ingenious device by which the plates are automatically changed in the air, without any attention whatever from the pilot. This striking British invention ha enabled many excellent and valuable photographs to be taken while the machine itself has been under heavy fire both from the air and the ground.

High-Speed Photography.

           Anyone who has tried to take a snapshot from the carriage window of an express train realizes the difficulty experienced in obtaining a negative entirely free from movement. The same difficulties are, of coarse, experienced in taking photographs from the air. A modern aero plane is really a traveling observation platform moving at from fifty to a hundred miles an hour. As the pace of the machine cannot be altered, the object to be taken must be "snapped" as it slips swiftly by beneath the machine. Aerial photography is, therefore, high-speed photography of a special kind. An aerial photograph is almost always under-exposed, and this calls for exceptional treatment when the plates come to be developed. Apart from this peculiarity, however, it is the definite policy of the Royal Air Force to specialize in very thin negatives. A dense negative takes far too long to print by artificial light. A thin negative enables prints to be made in about three seconds. In this way a trained Royal Air Force photographer can print and develop as many as eighty separate enlargements in the course of an hour.
           For this scientific work the Royal Air Force has trained large numbers of highly skilled workers. In the model dark-rooms at the Central School of Aerial Photography every candidate for acceptance as a R.A.F. photographer must first pass a severe test, designed to reveal his suitability or otherwise for the work. He is then given a month's practical intensive training, particular attention being paid to the processes of development, and to the enlargement of negatives by artificial light. Much importance is attached to the rapidity with which these enlargements ran be produced, for the fate of a battle may depend upon the promptness with which large scale copies of a vital subject can be supplied to the Intelligence Staff. After a further course at a training centre in England, the airman-photographer would proceed to a service squadron overseas and be assigned to a photographic section working with a recon naissance Bight. Such a "section" usually consists of a technical non-commissioned officer and about seven men, who take in torus the more confined and laborious aspects of the work. One man will “load” the magazines with unexposed plates, another will fix the cameras to the machines prior to flight, and receive them on return; others are detailed for developing, washing, drying, and plotting the negatives. Several men are constantly engaged in tin enlarging room, exposing and developing as many as 100 prints in an hour.

Before an Offensive.

           It is during the strenuous days preceding a big offensive that photographic activity raises to its maximum. During the successive big drives made by the British in France during the summer and autumn of last year, the entire field of operations was photographed over and over again. If a new series of enemy trenches were constructed during the night, a R.A.F. reconnaissance squadron would bring home photographic evidence of the fact on the following morning. It was no uncommon thing for as many as 11,000 negatives to be made on the Western front alone during a single week preceding an important advance.
           In addition to this vast work of aerial reconnaissance, photography was also extensively used for verifying the results of artillery fire, and for recording the precise effects of bombs dropped from the sir. The very Inking photographs of Frankfort, Mannheim, Mets, Sablon, etc., recently published in the Press, were actually taken during the raids upon those towns. Another valuable development was the application of the stereoscope to war intelligence. By taking two photographs of the same object, say an enemy trench system, at an interval of a few seconds, a striking stereoscopic effect is obtained which throws all the ramparts and other elevated portions of the enemy work into high relief. In this way the principal difficulties to be encountered by the attacking party can be foreseen.
           Aerial photography is destined to become one of the big new industries of the future. The topographical surveys of to-morrow will be photographic surveys; the school and commercial atlases will be photographic atlases. Exploration, commerce, scientific research must all benefit by an industry which may well grow to very largo proportions. In this field of post-war industrial activity, Britain will inevitably take a foremost place, for she already has at her command in Royal Air Force personnel some of the most highly trained specialist photographers in the world.

Practicus In The Studio: Backgrounds

           The modern photographer regards the background of a picture in a very different light from his predecessor of twenty, or even ten, years ago. Then it was the custom to use elaborately painted scenes, which were supposed to be more or lees suited to the social standing of the sitter. Usually they were highly incongruous, and we often found such combinations as a butcher-boy in a tropical conservatory or a lady in evening dress waiting by the banks of bonnie Loch Lomond. I well remember one enterprising firm who went so far as to have the entrance to Hyde Park accurately reproduced with real posts and rails for church parade sitters, and an interior of one of the salons in Buckingham Palace for court dresses. This sort of thing was borrowed from a certain school of portrait painters who considered it necessary to depict their models in what they considered an appropriate entourage. Fortunately we have changed all that, and the scenic background is rarely used except in the "while-you-wait" studio, where it serves to cover up finger-prints and stress markings in other words, it has almost entirely "retired into the background." The painter had one reason for introducing scenic effects into his pictures which does not apply to photography, for his subject being fully coloured often called for a foil, a warm-toned curtain, or sometimes even a conflagration, as in some naval or military portraits being used to modify a rubicund complexion, while a delicate sky or light foliage served to enhance the charms of a blonde beauty.
           The modern photographer has evidently taken a lesson from stage lighting, in which a concentrated light is often thrown upon the principal character, while the garish colours of the scenery are allowed to remain in semi-obscurity; and this has been all to the good as far as the artistic nature of the result is concerned. Many photographers now confine themselves to plain backgrounds. It is a safe course, although one sometime, (eels that a little relief would often be acceptable, especially for half and full length poses. Hence a dark cloud or suggestion of foliage is often useful, as it allows the figure to show more relief by opposing a light portion to the shadow side of the sitter. There is one disadvantage in using this class of background because it is not always possible to bring the light patch into the desired position. This was overcome by a device, little known in this country, which consisted in having the background made in an endless belt running over two rollers, something like a roller towel, by which the height of any portion of the surface can be adjusted to a nicety. Such a background may carry foliage suggestions, clouds, and plain surfaces in various sections, as the length of 16 ft. affords ample room. Another device for securing gradation was to have the ground made in the form of a shallow saucer, which gave a perfectly natural effect of light and shade just where it was wanted. Such a construction was found in practice to be too unwieldy for general use, and a more convenient way of carrying out the same idea is to have a tall screen made of narrow strips of wood glued to an ordinary plain canvas background of a medium grey tint. This can be placed so as to form a kind of alcove behind the sitter, more or less concavity being given as harder or softer gradation is required, or even be used flat, while when done with it can be rolled up and put in a corner. To make the method of construction quite clear, I will compare it to the roller shutter of a studio dark slide, the wooden slips being, of coarse, turned away from the sitter. Tapestries and curtains form effective backgrounds if judiciously used, but neither the pattern nor the folds should be pronounced in character, only enough being shown to break up the flatness of a plain surface.
           The illumination of the background has an important effect upon its depth of colour, and much may be done by turning it to or from the light, while the distance it is placed under the drawn blinds gives somewhat similar modification. Thus, to obtain the darkest effect from any given tint of grey, we keep it well back from the sitter and bring the edge nearest the side light as far forward as may be, the reverse being done when a lighter tone is required.
           In the case of white backgrounds for "sketch" work it is usually recommended to light these independently by opening the blinds behind the sitter. This is all right in a dull light, but on a bright day the flood of light so projected into the lens is very likely to cause a general fog over the negative. Certainly if the quality of the work is to be considered it is better to secure opacity by Mr. Adamson's method of using red ink and seccotine on the back of the negative. A common error is to paint sketch backgrounds a bluish-white, the idea being that a denser deposit will be obtained. This is quite wrong ; nothing can be whiter than white; the blue only masks any yellow tint in the distemper, and there is no gain by adding it.
           From time to time attempts hare been made to print in backgrounds from film negatives interposed between the portrait negative or to put in backgrounds on the back of the glass. These plans are rarely satisfactory, though in some cases excellent results have been obtained. As a rule, however, the general effect is not so good as from a background which has been photographed with the sitter.
           The materials used for backgrounds are various. For plain tints Melton cloth is excellent when it can be obtained. Failing this, distemper on canvas or stout sheeting is very suitable. For graduated backgrounds distemper may also be used, but it requires a considerable degree of skill to apply it, so that the necessary softness is obtained, and for this class I therefore prefer flatted oil-colour, which does not alter in depth upon drying, and which can be easily worked and softened while wet. Aerograph work upon a plain grey distemper foundation answers very well, but it takes some time to cover so large a space. The aerograph is also excellent for subduing contrast in scenic backgrounds which are too contrasty. I have also improved such by rubbing on black chalk powder exactly in the same way as in finishing an enlargement, but care must be taken to avoid patchiness if there are decided brush marks on the surface. For small grounds up to 54 in. wide dark green or red serge is very good, and a little light may be introduced by dusting powdered French chalk on where required. This is easily removed with a clothes-brush if the plain surface is again required. If you wish to distemper your own backgrounds it is better to purchase one of the many ready-made distempers or to use the Kalko powders (Vanguard Co.). which are specially prepared for this work. Oil-colours should not be purchased ready mixed; they should be procured "ground in oil" in a stiff paste, and this should be thinned down with turpentine or on of the current "turpentine substitutes."
           Lincrusta and Anaglypta are useful for making imitation panelled backgrounds. The latter, being a kind of embossed papier mache, is the cheaper, but will not stand knocking it so well as the Lincrusta does.
           Now that we do not require so many backgrounds the old-fashioned multiple stand should be discarded and the material should be stretched upon light wooden frames fixed upon feet with castors, so that they may be moved about the studio easily and used at either end or diagonally, as may be desired. It is a good plan to have the ends of the studio finished so that they may be used as backgrounds. This has also the excellent fleet of preventing the space behind the movable screens being used as a receptacle for lumber. The oak paneling comes in very well for this, and if the entire end be covered a large group can be accommodated without having to eke out the ordinary-sized ground with curtains, side slips, and other make-shifts.
           As a guide to those who are attempting to make or renovate their own backgrounds for the first time, I give the following hints. Do not expect to get an even surface with one coat of distemper. You may do so but, if not, do not be discouraged, apply a second coat rather thinner in consistency. If working on new canvas or sheeting it is a good plan to give a first coat or filling of thin size, or even starch or flour-paste. Tins prevent the distemper from being sucked into the material, and makes it easier to apply. For oil colour, ordinary glue size is to be preferred. A large paint brush, about three inches across, is easier for the amateur to manage than the orthodox distemper brush, and should always be used for oil. Work quietly, and do not slop on too much colour at once. A good grey can be made by mixing a little Venetian Bed and blue with the black and white. This looks warmer, and photographs better than black and white alone. Remember that distemper dries many shades darker than it appears when wet; therefore before using your mixed colour try a patch' on brown paper and dry it before the fire: you will then know what your background will look like when dry. A very little white will turn black into a light grey. Do not buy black in a dry powder, as it is very difficult to mix; ask for black ground in water. Always strain your distemper through muslin before using, or eke you will get streaks which are caused by unmixed particles of colour which break up under the brush.
           There is a right and a wrong way of nailing a background on to its frame. The wrong way is to fasten all four corners and then to go round the sides. The right way is to drive a strong tack in the middle of the top edge, then to pull the canvas as tightly as possible and drive another tack in the middle of the bottom; then fasten the two sides in the same way. Having got a straight pull these two ways, begin driving in tacks about one and a-half inches apart towards the corners, always working from the centre. In this way any fulness is drawn out as you go on, and the background will be perfectly flat and free from wrinkles. It is a good plan to fasten a loop handle tit iron or brass at each side of the frame; this obviates the necessity of handling the edge of the wood, and keeps the background in much bettor condition. If the frame is wider than you can stretch, a loop of webbing or cord, about eighteen inches long, should be fastened to one of the handles. Holding this and one handle, you can easily move an eight-foot frame single-handed, although if good castors are fitted it may not be necessary to lift it very often.