Sunday, July 13, 2008

EX CATHEDRA: Cheaper Plates; Supplementary Flashlight; Packing Negatives; Field-Camera and Cycle.

Cheaper Plates.

        It is announced that the prices of dry plates have been reduced as from March 11th last. The reduction brings quarter-plates to 3/- per dozen, half-plates to 6/6, and whole-plates to 12 3. Taking the quarter-plate as the basis of comparison it will thus be seen that the reduction to 3/- - from 3/8, which was the figure reached at the last rise on August 1st, 1918, amounts to a fraction over 19 per cent. The present price of the quarter-plate, in comparison with the pro- war figure of 1/3 per dozen, is still 140 per cent, higher. The schedules issued by the
Plate-makers give the complete figures of prices for extra rapid and ordinary plates, panchromatic and X-ray plates in both the English and metric sizes.

Supplementary Flashlight.

        Photographers as a whole are not fully aware of the advantages that flashlight has to offer as a supplementary illuminant when making exposures under difficult conditions. It sometimes happens that a certain amount of day or artificial light is available by which the exposure has to be made that is, in. sufficient of itself to light certain portions of the subject sufficiently for them to be fully exposed before the more brilliantly illuminated parts were hopelessly over-exposed. It is under conditions like these that the flash-lamp, which need only be of a simple form, or which may even be dispensed with if the prepared powder, such as Johnson, is employed, becomes of real assistance in solving the difficulty. We may, in explanation, cite an instance of this which occurred in our own work some years ago. The subject was an interior of an ancient abbey, the building badly lit through stained glass windows, two of which were directly facing the camera. The details of these windows, which were, of course, fairly well illuminated, were required in the negative together with a good rendering of some dark oak choir stalls in the foreground which were very badly illuminated indeed. A plate was exposed by meter for the windows, and just before this period was complete a strong flash was fired, sufficient to illuminate the whole of the interior. Careful development produced a negative that was "just right" for its purpose. The flash should be fired almost at the end of the exposure; if this is done before, there is a tendency for the smoke from the flash to cause a belt over the picture. The above indicates some simple means of overcoming difficulties due to bed illumination, and may be noted by commercial photographers who often are expected to produce first-class results under very unfavorable conditions of lighting. Some may be inclined to adopt the usual reflector and diffuser in connection with the flash, but though this may at times be desirable when dealing with very irregular lightings, we prefer to increase the flash in strength and keep further away from the subject if the building will admit.

Packing Negatives.

        Even in such simple matters as sending a negative through the post there are pitfalls for the unwary of which anyone to whom negatives come is being constantly reminded by the receipt of parcels of glass shattered to atoms by the thump of the post office stamp. Enlarging firms who would caution their customers ought to arrange for them to visit the sorting floors of a big postal depot. It would provide salutary warning against packing negatives between pieces of card or with no greater protection than the cardboard plate box in which they travel at the risk of their lives. Now that so many pursue the photographic process no further than the making of the negative the safe transit of the developed plates to the enlarger is as important an item of after-treatment as intensification, yet many people seem not to know that to make perfectly sure of its safe arrival the negative should travel in a wooden box so that the walls keep the shock of the defacing stamp off it. If it be prevented from shaking about in the box by cotton wool, wood shavings, or even crumpled paper above and below, the sender may challenge the Nasmyths of St. Martin's-le-Grand to do their worst. One other little precaution should be noted. If several negatives of different sizes are being sent together they should be placed so as to prevent the smaller bearing unevenly on the larger. For example, a quarter-plate should not be sandwiched between two half-plates, but be laid upon them with a piece of card between.

Field-Camera and Cycle.

        Those photographers who reside in country districts and have occasionally to carry a heavy field camera and tripod upon a cycle realize that if care is not taken such means of transit are likely to have a very detrimental effect upon their apparatus. The best place for the camera case is without doubt upon a strong back carrier firmly secured to the machine, though some workers have a preference for the front carrier. In the latter position there is a greater tendency for the camera to be shaken about, while if a proper carrier is not used there is a certain strain upon the aides in guiding the machine, especially if the instrument is a heavy one. Even on a back carrier there is a tendency for the case to get badly rubbed, and even the instrument itself may be scratched if a little care is not taken as a preventive. Some time ago, after a cycle journey of some miles across badly made roads, we had the experience of a camera case rubbed right through by the vibration between it and the cycle carrier, together with a broken plate in the dark slide, which necessitated a further journey for the purpose of making another exposure. Since then we have prevented such trouble ever recurring, very simply, in the following manner. A couple of strips of felt about two inches m width and about an inch in thickness, such as may be bought for a few pence at any saddler's, is placed the bottom of the camera case for the instrument itself slides to rest upon, and another strip of felt is I upon the carrier before the case is put on. The felt will absorb some vibration, and the troubles detailed above will not be encountered. We have also adopted this idea when traveling on a motor cycle, when is equally successful. The best place for the tripod is across the handle bars or along the top tube of the cycle. Such a plan is far better than slinging the case upon the operator s back when, if the instrument is a heavy one, its weight is soon felt.

The Future Of Aeroplane Photography

To pass into history – 1917 year.

[The following article, which we reprint from our American contemporary "Aviation," very properly raises the question of the commercial future of photography in the air, in which there are certainly as great possibilities as in aerial navigation generally. The fact that one of the authors, Mr. L. J. R. Hoist, is a camera designer and instructor should emphasize to manufacturers of apparatus the field which is opened by the application of aerial machines to practical methods of surveying.-EDS. "B.J."]

            The commercial future of aeroplane photography is not generally appreciated by aeroplane builders, since they have not as yet realised that preliminary surveying of high-roads, railroad, and other through routes can be done quicker and more cheaply by aeroplane photography than by any other know method. This is largely due to the circumstance that cameras have been hitherto considered as instruments of mere detail in the aeroplane industry as a whole, while as a matter of fact they will probably become one of the most important factors in the development of commercial aviation.
            The most fruitful field of commercial work for the aero plans camera in the United States will undoubtedly be the completion if the topographic survey of this country, which work includes the complete detailing of maps not yet complete, as well as the mapping of territory which till now has not been charted at all. To this already extensive programmer should be added the locating of the high and low water lines along our coasts, besides work of more local interest, such as the production of correct maps of smaller communities for real estate records, the location of sites for dams for irrigation purposes, locating railroads and waterways through mountainous country, establishing aerial routes and emergency landings in vast wooded tracts, etc., all of which work can be done in a fraction of the time, and hence for a fraction of the cost entailed by a complete manual survey.
            It should, however, not be understood that the aeroplane camera renders manual surveying obsolete. On the contrary, it is recognized that the camera does its most, effective work in connection with the slower but extremely accurate work of the surveyor, each one being checked up by the work of the other. In fact, it may be stated that the camera furnishes the fellahin details to a degree of perfection not attainable or, at any not obtained by manual survey whereas the latter produces a series of exact points of location which serve as control points for the data furnished by the camera.
            To obtain useful commercial mapping results from an aero plane requires different methods of operation than those used to make the so-called mosaics, because maps will be made between control points often many miles apart, between which it will be necessary to fill in not only the general ground plan bat also the contour lines.
As a matter of fact, the mapping use of aeroplane photography has been to a certain extent set back by the war, for the reason that certain scientific views, which are not relevant to commercial photography, rather held the foreground. These were questions of emulsions and lens-openings, neither of which is really of as much importance as the purely mechanical sides of the problem.
            Since all work enumerated before it this article is strictly of the order map-making, only such photographic apparatus as is adapted to this class of work need here be noted. This excludes all hand-held or hand-operated cameras as well as any semi-automat or non-automatic instruments which are rigidly attached to the aeroplane, since they partake with it in all its deviations from a perfectly horizontal position while in flight, a condition which is entirely incompatible with results for map-making. This leaves thus the freely suspended camera for further consideration.
            The military use of the aeroplane camera, during the war has led not necessarily form correct precedents, became of the assumption that an observer is essential. This has led to undue emphasis being placed on hand-operated or semi-automatic cameras which were to be of such simplified construction that no imperfect functioning would under the hands of the operator-observed. These military conditions do not prevail, nor apply, in commercial aero plane-mapping.
            A derision of opinion has existed relative to the automatic functions of aero plane cameras among the Allied Governments, but in n case were these difference caused by the requirement of aerial photographer mapping.
            Paramount importance was attached the chemical side of aerial photography much attention being devoted in particular to the perfection of color sensitive emulation to more readily camouflaged objects from the real ones.
            No doubt this aim is worth while but since existing emulsion used with suitable ray filters were apt to produce under the rough and ready condition of actual field photography behind the lines similar if not better remits with a far greater degrees of like hood to get any remits with a far greater degrees of like hood to get any results at all it must be regretted that these efforts placed the much more important mechanical side of the problem entirely in the shadow.
            As long as the question of aero plane photography was a question of filling in maps with nearby control points the detail design of the camera was not of the highest importance. To take a series of views over well-known ground is a problem comparatively simple but commercial application of aero lane photography requires more definite information in regard to drainage, divides and general contour information at otherwise the main benefits of rapid surveying cannot be obtained. Photographic aero plane surveying will unquestionably be used largely as a supplement of the Photo-theologize and other more common methods of surveying, to fill in between control points established by the older methods. But in the case of the more or less unknown country between control points established by the more common methods and for such works a coast surveying arises the greatest need of aeroplane survey.
            Surveying to be done from an aeroplane, particularly for filling in large areas, most is obtained by means of an automatic camera. On considering the problem of commercial aero plane photography it will soon be possible to pick out the necessary elements of design, and why an automatic camera should be used.
            All photographs to be used in map making must be a true horizontal projection of the earth's surface. In this way all points are practically reproduced by the photograph on a scale which is equal to elevation divided by focal length of the lens. If the plane of the photograph is not approximately parallel to the plane of the earth's surface (not considering the curvature of the earth), positions will not be correctly rendered; there is distortion to location which is equal to the cosine of the angle of inclination. In actual military practice, however, any camera installation which fastens the camera to the plane so that in the average flying position the camera is approximately horizontal was considered sufficiently well for purposes of making mosaics.

Contour Mapping.

            However this is by no means an answer to the question of obtaining survey information, as in the case of obtaining contours from aero plane photographs these can only be done by making use of the lens axis of the camera. The only way of establishing a true parallel position of the negative to the assumed plane of the earth is by means of the vertical position of the axis of tin- lens. Moreover, the only known factor for determining contours needed is the angular relation of the axis of the lens and its true focal length. With these two know factors the position of the earth can be graphically reproduced, and by ordinary drawing instruments a series of exposure points in the air can be determined. These exposure points are then used by transference of angles to reproduce graphically the location of points on the ground in space above or below the base line, which is usually taken at the foot of one of the axial points of the series of photographs.
            To obtain a vertical position of the axis of the lens necessitates a free suspension of the camera in the body of an aero piano where it is not affected by the air current in motion. This is easily done by patting the camera in the Gimbals suspension similar to a ship's compass. However, it is necessary to maintain a constant position, as otherwise the variation in the rate of the aero plane through the air would introduce a pendulum action in the camera. There are only two ways whereby this can be done first, the use of a gyroscope, and, secondly, the use of gravity and suitable air cushions to prevent oscillation, but at the same time to allow motion relative to the swinging plane. In practice the latter method is it introduces no mechanical complications and the accuracy resulting is close enough for mapping purposes.
            In to the requirements of angular position, aero plane photographic surveying requires a large number of photographs in a single flight. It is next to impossible to change plate magazines or to fill holders in flight sufficiently rapidly to obtain an unbroken series; moreover, it is necessary that photographs should be taken at what is practically a constant, interval between exposures; if not, there is very apt to be a break between two successive exposures which requires an additional flight to obtain the necessary information with which to fill the gap.
            In a military sense, during the recent war, this matter was not of such importance as it becomes for photographic surveying, for the reason that usually photographs were wanted of a single spot only, and intervening places were not necessary, although at times desirable. This has led to the use of film cameras using roll films having as many as 100 exposures to each loading.
            The principal difference between different makes of cameras for purposes of making military mosaics are usually matters of obtaining necessary power to change plates or film negatives.
            Three methods of obtaining power have been used: the air fan electricity and spring motors.
            In considering the design features of the camera it is very necessary to know to what extent photographic surveying will be carried out. If military mosaics are required, which generally are used simply to fill in small areas, a semiautomatic regardless of form of drive even a hand-operated? Camera -may be useful. If contour surveying is to be done it becomes necessary to have a very accurate timing device for the interval between exposures, as otherwise the overlapping relations between exposures will very easily be lost. The European continent is so thoroughly surveyed that the contour method has been very little used, and in the considerations of the necessary types of cameras, contour mapping has not been considered an essential feature. For this reasons the so-called automatic or semi-automatic camera ordinarily in use is not completely automatic, but simply is a power-driven mechanism which changes a plate or film negative and in which the actual exposure is made either by the or observer. There is only one completely automatic camera in existence which operates at varying rates of speed, controlled with certainty either by the pilot or the observer. This camera the Brock camera will be described later in detail.

The Triple Lens Camera.

            When making flights for map-making purposes a given area of grand can only be fully covered if a number of flights in parallel courses are undertaken, each new flight following a course just overlapping the strip of land covered by the previous flight. The number of flights required to cover a given width of territory will then be directly proportional to the width of the strip embraced by the photographs, and consequently it is desirable to embrace as wide a strip of land as practicable in each view.
            This consideration has led to the construction of triple lens cameras, the central lens pointing straight downward, and the lens on either side placed under an outwardly slanting angle. These three lenses are in one vertical plane at right angles to the direction of flight. The image-planes of the outer negatives are then usually set at an angle of 45 deg. to the central lens. These cameras are arranged for rigid attachment to the aeroplane. The two outer lenses will then produce pictures of strips of land extending far out at each side of the line of flight, whereas the central lens registers the views directly beneath the aeroplane and immediately adjoining regions.
            Although this arrangement undoubtedly covers a width of territory not obtainable with a single lens, it introduces difficulties which seem to far outweigh its possible advantages, and at its best it is only suitable for use on fairly flat ground. The complications arising from (three different planes of projection, and the necessity of afterwards reducing the two outer planes to that of the central one, without definite knowledge of the actual position of either plane at the instant of exposure constantly serious obstacles to the usefulness and commercial adaptation of devices of this kind.

Timing Exposures.

            It seems now preferable to obtain increased width of the strip of land depicted on the photography by increasing its width and reducing the focal length, of the lens, both to such limits as sound photographs and optical practice allow. A camera arranged to take negative. 5 x 7 ins., the 5-in. side in h line of flight and equipped with a lens of 8 ins. equivalent focus, embraces at 5000ft. elevation on each picture a strip of land 4,375ft. Wide and 3.125 ft. long on a scale of 1/7,500, or, if elevated to 6.666 ft., would produce pictures on a scale of 1/10,000 embracing 5,833 ft. in width by 4,166 in length. Most of high-grade lenses at 8-in. focus and openings of /'5 6 will cut a 5 x 7 in. image sharp and without distortion, and are serviceable for such work.
            The succeeding exposures should be timed at intervals of distance depending on the elevation and corresponding length of ground taken by the picture. The speed of the flight translates this distance interval into a corresponding time interval. It is thus desirable to provide means by which the actual time interval can be varied according to these conditions and which will operate with dependable precision in its various adjustments.
            As the manufacturers of the Brock Automatic Camera, it is probable that our actual experimental work in photographic surveying and in the design of cameras to obtain these results has been carried far beyond experimental work in this line by any individuals or by any of the Governments who have participated in the European war. The system of installation which we use has been found to permit exposures of from two to five times the exposure possible with any other system of installation, with all its attendant benefits. No other camera has been successfully built -with a system of free suspension, with the result, also, that no other camera has been built which can also do contour surveying. The importance of contour surveying in a military -sense was becoming recognized as the war drew to a close, and consequently this field of endeavour has had but a fraction of the effort put on it which will be devoted to it in the next few years.
            Another feature of camera design which originated with the Brock camera was the use of film for military purposes. The Brock film camera has been made successfully to use film in two sizes: one 4x5 ins., using ordinarily a 12-in. lens, and one 8 x 10 ins., using a 24-in. lens, both types completely automatic. These cameras were the first ones used which entirely eliminated static electricity in the film, and are to-day the only ones in which static electricity never occurs. The system of obtaining large negatives on film without distortion through the use of a glass support originated with the Brock 8 x 10 in. cameras. However, the use of the large negative sizes will be confined to military purposes, as for commercial or ordinary Government mapping a very large scale is not required.

The Brock Camera.

            Let us now consider some of the mechanical details of the Brock 4x5 in. camera and the reasons for the design. This camera is the outgrowth of a series of experiments to obtain a free suspension camera, motor driven, within reasonable weight, certain of operation, and controlled from a distant point, for use in a single-sealed aeroplane.
            Mechanical experiments led us into the design of the spring motor-driven cameras and resulted in our finding commercially feasible means of controlling the speed of operation of the spring -motor not in any way dependent on friction. The entire engineering profession is aware of the difficulty of obtaining a satisfactory variable speed friction drive which includes both certainty of operation and certainty of speed. In the case of a spring motor this difficulty is emphasized because the control through friction must be done fey the introduction of a governor. Such a construction results in absolute loss of control of speed regulation owing partly Ito the different percentage of friction due to moisture in the air -in varying amounts. The system we use, therefore, is the control of the main spring motor by means of an auxiliary spring motor, which is in effect a clock with a speed regulation of 3*(1/2) to 1. The importance of accurate speed control in the case of the Brock camera is greater than in any other camera, because of its ability to produce contour maps. Wherever it becomes necessary to obtain contours the axial point of the succeeding and the preceding negative must show on each exposure, with the result that exposures must occur at frequent and constant intervals without interruption, other wise a break will partially destroy the value of the contour photographic flight.
            Without any exceptions worth mentioning, all aerial cameras are fitted with focal-plane shutters, as the high efficiency of this type shutter, together with its extremes mechanical simplicity, renders is superior to the between lens shelter. In the Brock cameras focal-plane shutters are prevailed with a fixed slot, the speed adjustment being obtained entirely by means of the spring tension. Spends are variable from 1/50 to 200 of a second or any similar range.

Shutter Speeds.

            Is connection with shutter spends of aero plane cameras it is of particular interest to mention that, owing to the almost absence of vibration obtained, shutter spends can be regulated entirely with regard to the elimination of image movement through traveling spend, and no regard need be paid to the effect of vibration. The requirements due to speed are very easily met. For instance, a camera as already mentioned, fitted with an 8ft lens flying at 5.000 ft. elevation and at 120 m.p.h., reprises no faster exposure than 1 20 of a second to give a sharpness corresponding to a circle of confusion of 14/1000 of an inch and with a speed of 1/50 of a second the circle of confusion will be only 5.6 1000 of an inch. This means that the gumball-suspension has the practical advantage of being able to photograph both earlier and later in the day than would be practical with rigidly suspended cameras, which are generally, used with minimum exposures of 1/100 of a second to eliminate as much as possible the effect of vibration. It also means that such focal-plane shatters can be made with wide slots to reduce the duration to the expense period and thereby the resulting distortion to a perfectly negligible minimum, which in turn eliminates the only meeting valid arguments against focal-plane shutters.

Evenness of Exposure.

            A perfect eventide of exposure at all speeds can easily be obtained by proper design of the focal-plane shutter, in fact so that the slightest difference in exposure plainly seen is aero plane films, since maximum and minimum density adjoin in two negatives of a strip of continuous pictures side by show no observable variation. Especially in the civil or commercial uses of aero plane photography do these various features come to their fullest signification and it is only on this account that they have mentioned in detail.
            Summarizing the status and development of aero plane photographic surveying is an art still in its infancy. Under the aeronautical trade recognizes the possibilities of this use of their product, and unless the engineering profession of the business realize its possibilities it is not likely that the growth will be rapid. It is an unfortunate fact that up to the present time the energy developed to the constructive surveying features of aero plane photography has been sun fined to, and understood by only a few people.
            The truth of the matter is that, in the first place the emission questions which have arisen in Europe are really matters of is serious consequence although a considerable amount of time and effect has been spent to change and to make special emulsion. Efforts have also been made in Europe to make emulsions sensitive to certain colour whereas similar is not better, affects could have been obtained with existing emulsions by the use of a co1our screen and lengthened exposures. Whatever efforts have been made in the mechanical direction they have been very largely in the direction of making a camera which could be operated by the average observer without any knowledge of photography or of mechanics is safe to say that if the motion picture industry which is now in existent had had a military use and military development, the present stage of perfected would never have been leached, as the mechanical side of the motion picture industry has received a tremendous amount of attention for years. High-class motion pictures cannot be made by anyone but a skilled operator, and in exactly the way the success of the future of aeroplane surveying is dependent upon operators learning about the necessary photography and mechanics of aeroplane cameras; but it must be recognized for the future of aero plane surveying that apart from the development of the negative and the printing of the prints aero plane photography is a matter which should be entirely in the hands of civil and mechanical engineers.

Aeroplane Photography and Commerce.

            The modern aeroplane has reached the static of development where the safety of operation and the certainty of operation are as good as of the average automobile of ten years ago. This means that an aeroplane can be used for some hours over entirely unknown country without any landing places: it further means that such country can be completely and correctly mapped without difficulty and at a very low expense compared to the present-day methods of surveying. It is quite possible that in the future preliminary surveys will be made for railroads, roads, and various water-works entirely by aero plane photography and that when the line has been decided upon a party will go out simply for the purpose of staking agreed-upon lines. If the aeroplane industry will devote as much attention to this subject as has been devoted to other commercial possibilities, a rapid growth can be expected. As foundation-stones have been laid, it is only necessary for a general interest in this subject to be awakened by the aero plane industry before possibilities, first as a internment enterprise, and then as a commercial enterprise for civil engineers will find general recognition.


Thursday, July 3, 2008

Practicus In The Studio: The Surroundings Of The Studio.

Previous articles of this series, in which the aim of the writer to communicate items of a long experience in studio portraiture, have appeared weekly since the beginning of the present year. It is not thought possible to continue the series to the length of that by the name writer which ran hrough the "British Journal" some years ago, but if any reader among the younger generation of photographers, and particularly those engaged as assistants, has a particular subject which might be dealt with, his or her suggestion will be welcomed. The subjects of the previous articles of the series have been as follows: -
Studio Exposures (May 24).
Artificial Lighting (June 4).
Printing Processes for Portraiture (June 5).
Studio Accessories and Furniture (June 20).
A Talk About Lighting (June 10).
The Camera and the Lens (June 12).
Managing the Sitter (May 14).
Backgrounds (May 20).

          Some writers on lighting in the studio have treated the matter as if all studios were alike, and that a set of rules, which should ensure any desired revolt if they were followed, could be evolved. There could be no greater error, for hardly any two studios are exactly alike; in fact, so great is the difference that an operator who has created quite a reputation for artistic work in one will fail dismally in another. It has been my luck to work in many oddly constructed places, but I have hardly found one where, with a little study and perseverance, decent results could not be obtained, the principal difference being not so mach in the appearance of the negatives as in she length of exposure necessary to obtain then. This, I hope, will be of some comfort to those who have found an otherwise eligible position for a studio, but are doubtful as to its possibilities in the way of lighting.
          There are two main points to be considered, one being the orientation of tile building, or its relation to the cardinal points of the compass, and consequently to the sun, and the other the presence of outside obstructions in the shape of walls, trees, or other objects. Regarding the first, I think that too much stress has been laid upon the necessity for a northern aspect for the glass side; in fact, I have known cases where a photographer has gone to great trouble and expense to secure this or even to reject a position where it could not be obtained. For instance, where it has been a choice between securing a good working length with in eastern aspect or too short s studio for good work, the latter has been chosen, simply from fear of not being able to control the light in the former position. This idea dates back to wet-collodion days, when it was considered essential to have a large amount of open light, and has been handed down from one writer to another, although we must not forget that even in those early days Mr. Valentine Blanchard, whose artistic ability has never been questioned, proved that the finest possible work could be done all the year round in a studio facing due south. I frequently work in a studio with a full western aspect, and find no difficulty in doing so, although I must confess that I should like it muoh better if it were a northern one. The reason for this is, of course, that in the latter one can get the same effect all day without altering the blinds, while in the former modifications are necessary as the light works round.
          To make the best of a studio so situated that the sun shines upon the glass, it is necessary to be able to coyer the whole of the light either with dark or white blinds or curtains as my be needed, but when I say white blinds I do not mean pea-soup colour, which is the normal tint in many studios. These intercept so much light that they are useless as diffusers, which is their real mission. Mr. Blanchard screened his sunlit roof and side with light frames, upon which tissue paper was stretched; but I prefer my favourite white nainsook festoon curtains, as they may be easily pushed aside when not required, end are, moreover, easily washed when soiled. I have worked in a studio glazed with ground glass, but found that there was too much glare, and when white blinds were used in addition the exposures were too long. It is almost needless to say that in a sunlit studio there must be no bare glass, the white blinds being the source of light, when they act much in the same way as if a sky covered with white clouds were seen through dear glass. The simile is, perhaps, not quite good, but that is as nearly as I can put it. In such a studio the inside walls must be rather dark or flatness will result, and the area of white blind used must be no larger than is necessary. If we consider the ease with which good results can be obtained with a single enclosed arc lamp we shall see that a very large area of light is not necessary.
          The second point that of outside obstructions is a more difficult one and every individual case must be dealt with as a special problem. During the past few weeks I have had to deal with two cases in which the trouble arose from the proximity of a high wall a few feet from the side light. In the worst one the wall was higher than the studio, and about nine feet away. It was of dark brick and how the previous occupant of the studio, for whom it was built, managed I cannot imagine. His work was certainly unorthodox, and he abandoned photography for the stage. Then during an interval it was occupied as a workshop, until its excellent business position attracted another photographer who decided to take the chance. The first thing to be done was to visit the owner of the wall and to ask his permission, to have it painted white; this he gave readily enough, and the next to stipple the side light halfway up with very thin zinc white paint. The necessary dark and white blinds were fitted, and even in this dull weather the results obtained are excellent, although, of course, the exposures are not quite as rapid as they would be in a more open position.
          Another studio was even in a worse situation, being located at the bottom of a deep well-hole surrounded by lofty houses. Before it was built I went on to the leads on which it was to stand, and certainly felt some misgivings; still it was there or nowhere, and as the prospective user was a wealthy man we decided to take the risk. There was toplight, and not too much of that, but, with the help of outside silvered reflectors, lighting was quite passable, and many excellent portraits taken in it. All cases are not as bad as this, but there are often obstructions which seriously reduce the value of a studio. Once I built a studio in a garden in the winter, and it was very satisfactory, but what a difference when the leaves came on the trees again! Fortunately, most were on my own ground, and were drastically lopped, and my next-door neighbor helped, bf cutting in one or two which still troubled me. It is wonderful what you can get done if you talk nicely to people. Here, again, I found that stippling the side light was an improvement, as light which would be nearly vertical is intercepted and dispersed in all directions. If rolled plate be used in such circumstances, there is a great gain in light if the ribs be placed horizontally in the side light; every rib becomes a little cylindrical lens, and throws light into the studio.
          In the case of an immovable obstruction which is very near the proposed studio, it is advisable if possible to raise the building, so that it will overlook the obstacle. A friend who found himself in this difficulty said afterwards that it proved a blessing in disguise, for he had to provide himself with an excellent workroom upon which the glasshouse was built, and he found this much more comfortable than the cramped quarters he had proposed using, and the extra cost was not great considering the value of the accommodation provided.
          When building or adapting a studio care should be taken to avoid minor obstructions caused by portions of the building itself; for example, I have seen a single slant studio in which the slant was obtained by throwing back the top behind the general line of the building, thus leaving a triangular piece of wall standing out at each end. This may not be serious in many oases, but if a front lighting is wanted it considerably curtails it, and this is more especially so when the studio is rather a short one, as the angle of light is then necessarily more acute. Great caution must be exercised in erecting a studio near vacant land, as there is no guarantee that another building will not be erected that will shut the light completely out. In order to secure the right to do this, a landowner will often erect a screen on poles so as to block any window on neighboring land in order to prevent any subsequent claim to "ancient lights."
          It is easy to realise that different situations call for differently designed studios. In the commonest case of difficulty, where there is top light only, it is desirable to have as long; a range of glass in the roof as possible, as we can them draw the blinds well over the sitter's head, turn him slightly away from the light, and get the effect of a high side light; such a studio should be built as wide as possible for this reason.
          Studios of moderate height with side light only do not, perhaps, come within our scope, but as they, in common with those with top light only, are capable of being improved by the addition of a supplementary artificial light, we mention, them. A top light may easily be produced under an opaque ceiling by using either the half-watt or an enclosed arc lamp in a metal reflector, which gives a strong though soft reflected light from the ceiling, while similar lamps may be used either to illuminate a white side wall or to give a direct side light through a diffuser. The mixture of lights is not at all objectionable, and, in fact, will hardly be noticed by many sitters.
          Difficulties in lighting will be minimized if the studio be wide enough to allow of considerable latitude in the placing of the sitter; it should be possible to work diagonally or evens quite across the studio, and it should always be arranged, if possible, that either end of the studio can be used.
          When inspecting an empty studio or the site- for building one, a very simple way of judging of its possibilities is to seat oneself in the position likely to be occupied by the sitter, and from there to note how much clear sky is visible, and the nature of any obstructions. This gives a good starting-point, and is better than attempting to judge the lighting, at all events, in the open air.

PRACTICUS.

Wednesday, July 2, 2008

Electricity and Photography In Warfare.

[The generation of electric current in places where no other source of light is freely available has of course during the active operations in Prance been an important branch not only of the Royal Air Force but of other sections of the army. Inasmuch as the use of such small installations are equally of interest to photographers in country places, we take the opportunity of reprinting from the “Electrical Review'' an article describing the use of such units of equipment. Without an installation of this kind a photographer most fall back either on flashlight or on one of the incandescent paraffin lamps such as the Blanchard, neither of which can be said to rival a portable electric plant for all such portraiture as requires to be done by artificial light. – EDS., “B.J.”]

           Having recently returned from France, where I have been attached to a photographic section of H.M. Armies, it may be of general interest if I place on record a few particulars of the work of these sections, and the part played by electricity and engineering in carrying out their functions.
           It must be clearly understood that these sections are not responsible for the actual taking of the photographs, as this duty falls on the Royal Air Force. The photographs cover quite a large range of subjects – such as front line and support trenches, panoramas of large tracts of country, large mosaics or photographic maps of certain parts of the country, “aerials" of particular spots, enemy gun emplacements, bridges and railways before and after bombardment, roads, etc.
           The duty our little party had to perform was to tarn out copies of these photographs in large numbers and very quick working, when necessary, night and day, to get the work turned out in time to be of service for the particular military operations they were required for – whether it was for operations on a large scale or for local raids or artillery work. To give some idea of the magnitude of the operations these small isolated and almost unknown "sections" of the Army carried out, I may say that work equal to 23,000 full-plate photographs was turned out in 36 hours for one of the big blows dealt at the enemy last August Having gone so far to show the extent of the work, we now some to the means of carrying it out, and this is where electricity and engineering played their part "in the game."
           As these photographic sections have to move with the armies, the apparatus is often being. dismantled, moved, and re-erected, and as the conditions vary with every more, retreating or advancing, the plant is put to work under a variety of conditions; sometimes the generating plant is resting on a few piles driven in the ground, and at other tunes on a good solid concrete foundation.
           The plant I was in touch with consisted of one Gardner 5-H.P. petrol engine, direct-coupled to a 3-kw. Holmes generator running at 500 R.P.M. These machines were, of course, mounted on one bedplate. A second set consisted of a Petter Junior petrol engine, direct-coupled to a 3-kw. Holmes dynamo running at 725 R.P.M., on a common bed-plate.
           The working voltage in the depot was 110, and as a steady light was very essential for the photographic work on account of the time for exposure, for printing, equalizing, etc., the supply to the depot was always taken from accumulators, of which we had two complete batteries, which were need alternately, one being charged whilst the other set was being uncharged to the works.
           These batteries were generally accommodated in a room or hut near the engine-room, and complete control of the whole installation was obtained by a switchboard in the engine-room, fitted with the usual meters, charge and discharge switches, change-over switches for switching in or out either generator on to either battery, and also for switching either battery on to the works.
           All outgoing circuits were controlled by switches and fuses on the main switchboard, and mercury vapour lamps, general lighting and night-light circuits, etc., were all separate.
           The batteries were put p in teak boxes, lead-lined, and fitted with lids, and each set had a capacity of 190 ampere-hours. These had a fair amount of rough usage during the various hurried removals, but kept up to their work very well.
           As photographic prints of each subject were sent to our works, and not the original negatives, it was necessary to make a fresh negative from each print sent in, and this often meant over 100 subjects per day. These were taken with the aid of Cooper Hewitt mercury vapour lamps, two tubes in series in one frame, and two complete sets being used. In the case of photographs requiring to be enlarged, a Westminster arc lamp and enlarging camera were utilised. All printing from negatives was done in special printing boxes, lighted either by half-watt or ordinary M.F. lamps, and the same remark applies to the equalizing boxes.

Gardner Petrol Engine

Gardner Petrol Engine.

           After being printed, developed, fixed, and washed, all prints were hung up in a drying-room heated by slow-combustion stoves and spirit flares, and the air was kept moving with two 12 in. electric fans. As the temperature in this room was generally about 120 degs., the prints were dry and ready for the cutters in a very few minutes.
           The water supply was generally obtained from a stream near which the works were always situated, and the water pumped up to a supply tank with a Pelapone pumping set consisting of a petrol engine driving a turbine pump by means of a V-shaped belt, the set being mounted on a wooden frame, and so arranged that when the pipes were disconnected, it could be picked up bodily and carried. The water supply tank was generally fixed on a wooden structure near the main shed or building, and the water supply to all the washing sinks was run in screwed iron pipes, although a quantity of hose pipe was used for connecting up to the pump and tank at various times. The quantity of water used would be about 2,000 gallons per day.
           Floats and indicators were used in and connected to the supply tank, and arranged with electrical contact, either to ring a bell or switch on a coloured light when the tank was either full or empty.
           The general lighting of the depot, which consisted of dark rooms, cutting-room, stores, office, engine, battery and pump rooms dining room, billets, etc., was carried out with ordinary M.F. lamps, and the general wiring was carried out on the cleat system, this enabling dismantling and re-erecting to be carried out in a very short time; I have known the plant to be dismantled and taken across country thirty or forty miles, photographic work being resumed in something like 48 hours. This, of course, was with a good deal of very temporary work, but the "military machine" had to be kept going, and the work of making a fairly decent job of the general installation had to be done whilst the place was kept working; very often, as soon as it was a, bit straight, another move would be ordered. However, as the production of these photographs in an efficient and quick manner very often meant the saving of thousands of valuable British lives and the destruction of those of the enemy, everybody worked with a will for a definite purpose.

Petter Junior petrol engine Petter Junior petrol engine.

Holmes dynamo Holmes dynamo.

Pelapone pumping set

Pelapone pumping set.


           The engineering staff consisted of another R.E. and myself, and the total works staff only amounted to 25, including officer, N.C.O.'s, engineers, dispatch rider, cook, storekeeper, and photographers.
           The illustrations show some of the plant as used and described, and I might also add that the switch used for the firing of the mines at Messines Ridge eventually found its way on to our switchboard.
           Such is a short account of one of the many cases where engineering and electricity, in particular, have come to the aid of our Armies, and have been used to advantage in helping to beat the Hun and save civilisation from a fate that was too horrible to contemplate.

H. Moss.

Thursday, June 26, 2008

Assistants' Notes: Sight and the Photographer.

Sight and the Photographer.

           IT goes without saying that sight is the most important bodily function from a photographic point of view. One might imagine an armless, legless, deaf or dumb person performing some job or other connected with the business, and even one with deficiency of intellect might posses some little photographic skill, bat a blind photographer is impossible.
           It follows that a photographer's eyes, good or bad, should not be neglected, but accorded at least a modicum of intelligent consideration. A good many pros. hold the belief that the practice of their craft is in itself sufficient ultimately to damage the sight, and judging by the number of workers one meets whose eyes are not so good as they might be, the belief seems reasonable. On the other hand, there are craftsmen of ripe age whose sight is still perfect in spite of yean of hard work. The fact is that photography can – not must – damage or even destroy the sight of anyone engaged at it, the damage usually being brought about by circumstances many of which are in themselves inconspicuous and therefore unsuspected.
           These circumstances depend on the nature of the work, each branch of the business having its own peculiar sources of possible eye strain. In the studio the eye may suffer from constant straining at a too thick or coarse focusing screen, or focusing with the lens stopped down. This is a small thing, but in a very busy shop when the operator may be behind the camera for bourn at a stretch, the strain will tell. Where roach focusing has to be done, as much light as passable should be allowed through lens and screen, and the work done smartly. Indecision ceases strain, and does not improve the final definition of the picture.
           The continual itching from abort to long focus, occasioned by looking first at the sitter and than at the screen, may tire an eye but if the eyes (and the general health also) are this should prove more of an exercise than a strain.
           Working with artificial light, an operator may damage his sight by allowing the light to fall directly on his face too often; in other words, by looking long or often at the lamp. Continual witching on and off from full light to semi-darkness, as also going in and oat between studio and plate-changing room, will leave its mark on the sight if carried on to a great extent. The moral here is to keep a fair amount of light in the studio all the time, and have an assistant changing. The latter can keep his or her gaze away from the bright end of the studio without any trouble.
           In the dark-room the red or yellow lamp is often blamed for tired or failing eyes. This is not strictly right, though the position and strength of the coloured light is very often to blame. A lamp should never be in a position to sand direct light into the eye when working, and for this reason a hanging lamp, shedding all its light downwards, is to be recommended. The strength of the light should be as great as the sensitive materials will permit. With regard to the printing room, I would say to those who can please themselves: Discard bromide for gaslight, have as much light as you would in your drawing-room, and be comfortable.
           Where yellow or red light is compulsory all walls should be painted vary light: it will obviate much eyestrain in groping about for things which are invisible.
With printing and retouching direct light is mostly used, but in neither case does it – so far as my experience and observation go hart the eye to the same extent as in the case of the dark-room lamp. The difference is this: in one case the eye is working with the image supplied by the direct light and nothing else, in the other the direct rays are worrying the eye and distracting it from its work. This can continue for a long time without the victim being aware of it, even though the eyes and the work may be suffering.
           For retouching, the use of direct light, however, is not compulsory; many workers prefer to work against a white or tinted reflector, and one retoucher I know claims that this practice is repairable for his sight being as good as it was twenty years ago. Retouching with weak light, particularly if the negative is yellow or dense ceases eye strain, while the remarks on dark-room lamps apply also to extraneous light near a retouching desk. Working on very small beads is apt to be trying, and for this a magnifier may lessen the strain, bat it should not be used habitually, otherwise it may become an indispensable crutch.
           Spotting and working-up require sight that if perfectly free from automation, and when done by anyone whose sight is not normal, and not corrected by glasses, this work will greatly aggravate the weakness. At the slightest sign of strain the lighting conditions should be examined, and if not at fault astigmatism should be needed and the eyes tested. Spectacles, however, are not likely to cure bad light; they will correct the vision and so do away with strain, but that is all.
           Before going any further it may be as well to say that this article does not pretend to deal with its subject from any but a purely photographic standpoint. The many defects of vision caused by such things as nerves, bad blood, cigarettes, etc., are not within my scope, and when a photographer's eyes give trouble it rests with him or his doctor to decide whether his craft is to blame or not; it is always possible that some outside influence is causing the mischief. At the same time, a few remarks on the care of the sight may not be out of place. Tired or overworked eyes can be benefited by bathing, and any chemist will make up an eye-bath cheaply. The simplest and safest of these is boric acid.
           Sight can be greatly improved by country walking, particularly in districts where long clear views prevail. In my own experience I find nothing to equal daily gazing at landscape the foreground of which is mostly green, with distant planes stretching to far off mountains. Unfortunately, we cannot always enjoy this kind of cure for tired eyes, but in any case and at all times it pays a photographer to care for his eyes, even if it means a little extra trouble. This applies particularly to young workers. In the vigor of youth details are not so readily noticed as they are in alter years, and a young enthusiast may go on working in conditions which are bad for the sight without worrying until the mischief is done. Years after it may cost a good deal to undo what a little forethought could have prevented. – THERMIT.

Wednesday, June 25, 2008

EX CATHEDRA: Complete Development; Colour of Second-hand Lenses; Camouflaging the Camera; Varnishing Negatives.

Complete Development

            The maxim which is rightly emphasized to makers of bromide prints, namely, to develop thoroughly, is one which even now, although it has been repeated over and over again, is largely disregarded. Neglect of it is one of the chief causes of unsatisfactory quality in sepia-toned prints, the results of toning an image which has been rapidly and, therefore, superficially developed being greatly inferior to those in which development has been carried more deeply into the film. One rule which has been given for the guidance of bromide printers is that the time of development should be at leant three minutes, and exposure adjusted accordingly in order that the print at the end of this period of development should not exhibit the effects of over-exposure. But papers and developers having their particular idiosyncrasies, perhaps a more usefully applied rule for discovering whether prints are receiving this "full" development is to immerse half of s print only in the developer, and after the expiration of, say, half a minute to allow the developer to act upon the whole. If, then, development can be continued so as to yield a satisfactory print which does not show a difference between the two halves, the worker may be satisfied that his development u of the required fullness. On the other hand, a difference between the two halves will indicate that exposure can be advantageously cut down.

Colour of Second-hand Lenses.

            Those who are baying secondhand lenses will do well to give the question of colour some consideration. As is well known, long exposure to damp or atmospheric conditions lead to discolor the glass of the lens, or cause the balsam cementing the components to deteriorate with the same result. Some secondhand lenses that we have seen suffer from this very badly, the glass having quite a yellow tinge, in others, though existent, the defect is not so apparent, but if present the marked aperture of the instrument does not represent its actual working speed. We had one inch lens that when examined in a casual way showed little or nothing the matter, but when placed against a sheet of pure white writing paper a slight discoloration was at once noticed Slight though this was, it had a marked slowing action when using ordinary plates, though when orthochromatic emulsions were employed this to a large extent disappeared. Those having such instruments will do well to send them to one of the firms advertising in the advertisement columns of this Journal for repolishing or recementing of the glasses as the case may be, while if buying a secondhand instrument prospective buyers should be on the watch for a defect, which, though it might easily peas unnoticed, reduces the actual value of a lens very considerably. This discoloration is perhaps more frequently met with in the older instruments than in the modern anastigmats, unless these have been very much exposed to bad conditions, but it is a condition of things that all owners of good cemented anastigmats will do well to guard against.

Camouflaging the Camera.

            We commented recently upon the use of the small camera in certain branches of photographic work where its advantages may be turned to good account. A further instance of its value as a supplementary instrument in the studio was told to us the other day by a professional friend. He was commissioned to make a portrait of a child of whom previous experience had taught him that, however pleasing might be the expression on the little sitter's face, it instinctively froze directly the operator made a move towards the camera. The studio instrument was prepared in the usual way, and in front of it was placed a table with piles of books, etc., very carefully arranged to conceal a previously focussed vest-pocket camera, with its shutter set ready for an exposure. The usual attempts were made with the studio instrument and with small hope of obtaining a satisfactory picture. The operator turned away rather disgusted. Almost at once the little sitter was herself again, and casually, as it were, turning to the table the operator pressed down the shutter release of the vest-pocket camera, covering the action as if by taking up a book. As was expected, the exposures made with the studio camera were failures from the point of view of expression, but the small camera yielded a lifelike and pleasing portrait. The negative was carefully enlarged, and the result was an order for some dozens of prints. The idea of camouflaging a small camera should prove of value to those photographers who have to take portraits of nervy sitters, since the exposure may be made at a selected opportunity without the sitter being aware of it. Such a plan should help in overcoming many a difficulty in this respect. Though the negative is small, the quality can be of the best, and the resulting enlargements with a little working-up should give no indication whatever that they are not contact prints from large-sized original negatives.

Varnishing Negatives.

            Few photographers at the present time varnish their negatives, nor when ordinary bromide printing or enlarging is to be the medium is this course really necessary. But when a number of P.O.P. carbon or platinum prints are required from one negative, and the printing is done in the semi-open air for the most part, in damp weather it is a wise precaution to give the negatives a coat of ordinary cold varnish. Many present-day operators, however, find a great difficulty in getting an even coat of varnish over the entire plate by the ordinary method, and if this is not done there is a tendency for the varnish to dry in ridges, which means, of course, corresponding markings on the prints. Varnishing negatives by flowing the varnish on and tilting the plate at various angles until the whole is covered, and then draining the surplus back into the bottle, is an operation that requires a certain amount of skill, which can only be obtained with practice. We have for some time past varnished our negatives with an ordinary camel-hair (or hog-hair) brush. The exact kind is not very important, provided that it is well made and free from loose hairs. For this method, though not strictly orthodox, we may claim that it is comparatively easy to put a light but even coat of varnish on the film. None of the varnish need be got upon the back of the plate, and negatives may be very rapidly treated. Care should be taken not to get the brush too full of the varnish, or uneven coating may result. To those who have had no experience of varnishing negatives this alternative method may be recommended, although the essential feature of it is that a thin coating is rapidly applied.

Sunday, June 22, 2008

Fog In The Studio.

           IN many localities, notably in the London district, the state of the atmosphere has left much to be desired from the photographer's point of view. Not only has there been an actual deficiency of light through the presence of more or less yellow fogs, but there has been great difficulty in securing brilliant negatives on days when the light was fairly good, because of the general haziness of the atmosphere. Many photographers suffer from this fogginess without quite being aware of the actual cause of it. A simple experiment which will show in a rough way how much fog is present in any room at various distances can be made with the aid of two ordinary black velvet focusing cloths, velvet being chosen because it has leas reflecting power than any other material in ordinary use. One piece of velvet is crumpled up so that some parts produce deep shadow and put on a table in the position usually occupied by the sitter. The operator then stands by the camera at the distance at which a full-length portrait would be taken, and holds up the other about a foot from his eyes so that it half covers the piece on the table. If there is any appreciable amount of haze present he will find that the deep shadows on the distant piece appear quite grey in comparison with those on the piece which he is holding, and at once finds an explanation of the flat negatives which he has been obtaining.
           Having established the existence of the fog, our aim is now to minimise its effects, and there are many methods by which this end may be partially attained which, when put together, result in a substantial improvement in the quality of the negatives. In the first place, the studio windows should be kept clean, so that as small an area of glass as will give the desired lighting will be needed to obtain short exposures. By thus closing out all unnecessary light we reduce the general illumination of the fog and get a much brighter image. This can perhaps better be seen when working with artificial light. If we build the lamps in with screens or backgrounds so that the light falls upon the sitter only and none reaches any other part of the studio, there are only three or four feet of fog to work through, while if the whole of the studio is illuminated the amount is greatly increased.
           In foggy weather the lighting of the sitter may be more concentrated than is usually necessary, as a more vigorous negative will then be obtained, and printing can be carried on until the shadows are of sufficient depth. Windows become coated with smoke in a day or two in the winter and act as undesirable diffusers, so that it is advisable to clean at least the panes which it is intended to leave unscreened.
           A fairly warm temperature and good ventilation tend to reduce fog and to clear it away quickly. We have often noticed that a room or studio has remained foggy long after it has become fairly clear outside. When the necessary power is available, an electric fan will do much to establish a current of air, which should be directed towards an open window or door. A proper exhaust fan fitted near the roof is the best form, but the portable ones are of considerable value.
           We have already pointed out how the effect of fog may be reduced by cutting out all unnecessary illumination. A further improvement may be made by using a lens of as short a focal length as possible, though not so short as to introduce distortion. Where sufficient length of studio is available, it is now common to use sixteen or eighteen-inch lenses for all-round cabinet work, and it is quite good practice in clear weather. But at other times a tea or twelve-inch lens will be found to give much brighter pictures. As a matter of fact, many photographers have found this out without knowing the reason, and attributed the improvement in brilliancy to some other property in the lens than its focal length. Whatever lens is being used, it should be kept clean. Lenses will get as dirty as windows do in a smoky atmosphere, and will then yield flat images in the clearest light. If a lens has not been kept clean it is interesting to take a negative with it before cleaning and one directly afterwards. In most cases the contrast will be striking. Lenses should be cleaned carefully, a vigorous rob with the corner of the focussing cloth is not to be recommended, as such treatment soon "greys" the surface. An old worn handker-chief, kept in a box free from dost and grit, should be used. If there is a greasy deposit from town smoke, a single drop of pure alcohol may be applied on a tuft of cotton wool, and then the surface quickly polished with the handkerchief.
           Although we are opposed to all “tinkering” methods of development, the judicious use of bromide upon exposures which have been made under adverse conditions is quite permissible. To describe the action of bromide in popular language, we may say that, when used upon an over-exposed or foggily lighted plate, it allows the high-lights to get a start before the shadows begin to develop. If the plate be developed right out this advantage is lost, but as most portrait negatives do not reach this stage there is a decided benefit to be obtained by the use of bromide in the cases we have mentioned. It is necessary to add the bromide to the developer before immersing the plate. Once development has started it is of little, if any, effect. The character of the plates used should also be taken into consideration. Some brands tend to give brighter results than others. These should be chosen for foggy weather, as, although the scale of tones may not be so long, the resulting print is more satisfactory.