CHEMICAL DRAWING V.
Photograph
EDWARD M. HOSHALL 2434 Guilford Avenue, Baltimore, Maryland
T
HE application of technical photography to the requirements of the chemist as a method of supplementing line drawings, exhibiting apparatus, indicating general arrangement of apparatus, demonstrating operating technic, and even replacing line drawings, has been to a large extent neglected. The use of difficultly executed drawings or sketches where a photograph would suffice to convey the information indicates that the chemist is unfamiliar with the rapidity and efficiency of photography as applied to his requirements. To present in detail the perspective and proportions of apparatus and material by line drawing is difficult and often impossible, whereas it would be quite simple to apply a few general rules of photography and obtain excellent reproductions of the original subject for the contemplated paper or publi. cation.
The films or plates depend upon the type of camera used. Films have largely supplanted plates, especially in smaller cameras; hence only the former will be considered. Since the time of exposure can he varied at will with inanimate subjects, it is not necessary to use a highly sensitive high-speed film. In general, most commercial medium-speed films are satisfactory. When retouching is contemplated, as for example, to add lettering or reference material to the negative, film fitted with a "matte-emulsion" should be selected, since this permits the use of a pencil for blockiag-out or retouching. The ordinary films for popular-type cameras are panchromatic high-speed films, which do not give the most satisfactory results hut which are nevertheless used for most amateur work. For the type of work we are discussing panchromatic film is usuallv unnecessarv, for form rather than color value is or&narily the essence of the illustration. SUBJECT MATERIAL I t may be pointed out that when photographing inhe range of subjects varies from the apparatus and teriors, where stray lights such as door openings and of microchemistry to laboratory, ex~eri- reflections from polished surfaces are allowed to fall mental, and plant equipment. Since all kinds and on the plate, considerable blurring may be produced types of subjects are to be considered under various at the edges of the high lights, hi^ is technically conditions of illumination, location, and other variable termed Mhalation.M B~ the use of specially prepared factors, the task of securing satisfactory reproductions plates or films of the "non-halation" type, very soft win depend upon the application of a few general con- detail may he secured under the most trying conditions. siderations and the ingenuity of the photographer. Most of the popular camera films are of the non-halaSince glassware and laboratory equipment are more tion type. often photographed the chemist than other subjects, when a greatdeal of photography is contemplated, these will be treated in some detail in the following a tripod which permits the adjustment of the camera paragraphs. to any position and which is firm and rigid when set EQUIPMENT up is most desirable. Flood lamps, projectors, light boxes, filters, and The commercial photographer has a wide range of cameras from which to choose, whereas the chemist, other equipment used by the commercial photographer who only infrequently uses photography, must usually can, with a little ingenuity, be borrowed or improvised restrict himself to a folding camera, or possibly to a on short notice. Tin dish pans with 500- or 1000"box" camera of the popular type. For a negative to watt lamps mounted inside make excellent flood lamps. be satisfactorily copied for reproduction, the original A wire band should be mounted around the outer edge print should be capable of being reduced in size. A of Such a lamp to permit the attachment of gelatin camera which takes a picture about 31/2inches by 51/2 filters if necessary. Spotlights may he constructed inches (8.9 cm. X 14.0 cm.) is about the minimum size from tin cans or tin plate if the necessary lenses are which can be expected to yield good results. If the available, or they may be borrowed from the local chemist is in a position to borrow or ~urchasea larger theatrical supply house. type, the 5 inch by 7 inch (12.7 cm. X 17.8 cm.) semiVarious other equipment such as material for backcommercial type with anastigmat lens is recommended. grounds, flashlight equipment (seldom used for photoMost folding cameras are equipped with a rectilinear graphs of this nature), and the equipment necessary lens which is far cheaper and more easily operated than for developing, fixing, printing, toning, and retouching the anastigmat lens, but which has not the advantage will be required if the chemist desires to enter this of equal minuteness of definition. field. 546
P R E P W O N OF THE OBJECT
Those objects which the chemist may have occasion to photograph may be grouped in general as glassware, metallic, and wood or composition material. Each type requires slightly different treatment. If correct films are used, with the correct illumination, it is not often necessary to prepare the objects in order to obtain a fairly satisfactory photograph. If, however, it is desired to obtain a degree of accuracy and detail in the photograph, such as should be used in technical journals, then the object should be prepared so as to give the clearest definition and bring out the detail required. In some cases the high lights of polished glass give rise to reflections which produce halation in the finished plate or film. In order to "tent down" these reflections, the glass must be treated to decrease its reflecting power. There are many methods of accomplishing this, probably the most convenient of which is to make a dilute suspension of whiting in water with a small amount of glue, and then by means of an air-brush (an ordinary spray operated by hand or from the laboratory pressure line) apply this "dope" to the surfaces to be photographed. This mixture is easily applied and readily removed by warm water. If nou-halation plates are used the foregoing treatment is unnecessary. Highly polished metallic surfaces may be dulled by rolling a ball of putty over them, or by applying finely ground chalk with a powder putf. Metallic surfaces of laboratory equipment have usually been painted black, or in dark colors which photograph black and which reproduce very dully and without detail. A slate-colored paint which will photograph well and bring out the necessary detail may be made by mixing white lead with turpentine and lampblack and adding a small amount of drier. This forms an excellent base and is readily removed with an oily rag. Other polished materials common to laboratories are usually dulled by applying powder from a powder puff and then gently rubbmg it in so that the grain, if of wood, or the type of surface may be shown. Where no special treatment of the subject is necessary one important point should be noted; that is, the subject should be scrupulously clean, since smears, stains, and foreign matter are plainly apparent on the finished plate. When it is necessary to bring out details in apparatus, as for instance to show the graduations of a buret or other types of calibrations, the parts to be stressed should be prepared by filling the graduations with powdered chalk, applying with a powder puff, and then rubbing in by hand and finally removing the excess. Chalked lmes or marks are frequently used to indicate joints or the junctions between sections. ILLUMINATION AND TAKING THE PICTURE
Textbooks and handbooks of photography seldom discuss the illumination of objects of glass or other transparent or semi-transparent material. There are
no fixed rules to define methods of securing correct illumination; the many variables make each photograph a special problem, and the method followed must usually be one of experience or of trial and error. The following general methods have been used and found to give excellent results.
Figure 1indicates the general arrangement for photographmg glassware. The subject A is illuminated by a back-light B, which may be a window or a ground glass with a weak light source behind it, and a front light C, a 1000-watt spotlight which is necessary to bring out the detail. Clean, unwrinkled, gray paper (blotting paper is satisfactory), or a blackboard which has been lightly dusted with chalk, may be used for the background D. The camera E is mounted with its centerline approximately coinciding with that of the apparatus. The combination lighting will give the general effect of opaquing the background, and a t the same time of bringing out the details sharply.
Another method especially applicable to small parts rather than to apparatus set-ups is shown in Figure 2. This method makes use of a "light-box," which consists of a square box open at both ends and lined with dull velvet, or felt, in order that reflections may be avoided. The subject A is placed in the box B, and a gray background C is arranged; an exposure is then made by the camera D using the weak front light E. After the first exposure the gray background is removed, a ground glass is substituted for C, and the small projector F is used to illuminate the subject A from the
rear. Another exposure, much shorter than the first, is then made. This is an ideal method of obtaining detail on small glass or other transparent material. It may be noted that if the room is made sufficiently dark and the front light source E is replaced by a weak spotlight, the box may be dispensed with. Where back-lighting is not used a suitable background will be required. The choice of a light or dark background will be governed by the subject being photographed. Figure 3 is an excellent reproduction that makes use of a light background, while a dark one is used in Figure 4. The background in Figure 5 appears to be of paper which is considerably creased, the result of which i s to give a poor ap-q pearance to the finished reproduction. Poor illumination has failed to bring out the detail in this photograph. Figure 6 is a satisfactory photograph of a small glass apparatus, although refinements, such as balancing the background (removing the shadows) and possibly giving more detail to the metal parts, would have made a better photograph. An example of an apparatus layout, in which the contrast between high lights and areas of density is too great, is given in Figure 7, which is entitled "Hydrogen-electrode cell and potentiometer system." The photograph is entirely unsatisfactory, in that not even the elements of the system are distinguishablmuch less their:connections. More
even illumination from the front, and a more uniform background (replacing the white material by a gray), and possibly accentuation of connections and important parts, as previously described, would have produced a more useful photograph. The detail of Figure 8 is fairly good, but the title "View of apparatus for the determination of smoking point of fats2'-would certainly not indicate that several bottles, an extra hot plate, a shield, and reagent shelves are required to complete the picture. A uniform background, exclusion of irrelevant apparatus, and possibly an attempt to indicate the electrical connections, would have improved the photograph considerably. Little can be said regarding exposure; the many variable factors usually make experience and the trial-and-error method the best rules to follow. When in doubt, take several exposures immediately after the apparatus has been prepared, remembering that laboratory fumes, dust, and dirt contribute to give poor reproductions by making smears and spots on the apparatus which show up vividly in the print. DEVELOPING, FIXING, RETOUCHING, AND PRINTING
No attempt will be made to describe these general processes in detail since in most respects the treatment of material for reproduction differs but little from ordinary art photographic processes. One point of difference is that a gloss finish should be used on all photo-
Lantern slides are often used by the chemist for demonstration and exhibition purposes. Tables,
by the use of a printing frame or holder. Exposure should then be made as in ordinary printing. If a portion of the negative is to be omitted a paper or cardboard mask slightly larger than the omitted section is made and placed between the printing frame glass and the negative. Another method of printing, termed "copying" or camera printing," makes use of a camera as in enlarging. By this method it is possible to select a portion of a negative of any size and print that portion on the plate, the size being governed by adjustment of the camera combination. The most convenient arrangement is a fixed-focus lantern-slide box with the negative to he copied placed a t one end and the lantern plate a t the other with the lens interposed between the two. Sharp definition is secured on a ground glass plate inserted in the lantern-slide position; the glass plate is removed and the lantern plate reinserted and
charts, and apparatus diagrams are presented to audiences more effectively and conveniently by the use of satisfactorily prepared slides than by any other method. The use of sensitized glass plates rather than sensitized paper for printing constitutes the chief difference between lantern-slide making and ordinary picture making. The general size of lantern plates in the United States is 3'/," by 4' (8.25 cm. by 10.2 em.). Making due allowance for margin a camera picture Z1/%'by 31/2v(6.25 cm. by 8.25 an.)is about the most convenient size to use. In the actual printing by the "contact" method, the first step is to place the negative in correct position relative to the sensitized glass plate, which may be accomplished most effectively
exposed by daylight or artificial light. A suitable apparatus may be improvised from a large plate camera and one of smaller size to accommodate thelantern slide. The two are mounted firmly with lenses toward each other. The lens of one is removed and the set-up is operated after the fashion of the fixed-focus lantern previously described. In general, development of the plate is more difficult than that of the film negative or paper print, since the requirements regarding transparency of a few square inches of photograph through which all light must pass to illuminate the screen are rather exacting. Using a standard developer, a satisfactory method of procedure is to keep the composition of the developer constant and vary the time of development over a series
graphs intended for reproduction. The degree of contrast between licht and dark areas should be somewhat higher than for ordinary work. If a picture is well taken it can usually be developed and prepared by the amateur, while, on the other hand, the commercial photographer is often able to produce a satisfactory print from a negative which is apparently worthless in the hands of the novice. For publication purposes especially, many amateurs prefer to have their plates or films developed by a commercial photographer. For those interested in these processes, however, selected references are appended a t the end of this article.
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LANTERN SLIDES
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for lantem-slide exhibition, care should be taken to make the work as perfect as possible since errors are greatly magnified. Lettering especially is often unsightly and should be used as sparingly as possible for this type of work. Care should also be taken to photograph the charts correctly and without distortion due to creasing or bending. Black ink only should be used. The quality of the average slide maie hv the amateur is rather ~ o o r . l'hc chemist ~articnlarlvshould strive to maintain his "visual reports" a t the same level of excellence as his accomplishments in the laboratory. The same summary applies to the other phases of "Chemical Drawing" discussed in the preceding papers, and it is with this thought and its implied challenge to those who would make chemical illustrations, that this series is closed. of plates. The novice should then compare his slides with one made by an expert, and thus approximate correct development. The ensuing steps of fixing, washing, reduction or intensification, and drying, are carried out in about the same manner as ordinary developing. It should be borne in mind, however, that all solutions should be filtered and that the apparatus used should be sc~pulouslyclean, since dirt or dust produce blemishes which are greatly magnified when projected on the screen. Some slide makers deliberately develop to a greater density than necessary and then reduce with a 10 per cent. potassium ferricyanide solution, which is most effective in clearing up the high lights and giving the slide a finished appearance. Mountina the slide consists of placing a cover glas; over the sensitive side of the plate in order to protect it against handling, lantern heat, and dirt. Gummed paper, or better still, gummed linen, should then be used to bind the cover glass to the plate, allowing about one-quarter inch (0.6 cm.) margin on the plates on both sides. When the slide is held in the correct position for placing in the lantern, a visible mark (a 5-mm. gilt paper star is excellent) should be placed in the upper right-hand corner. In the preparation of charts, curves, and diagrams
I n d . O Ens. Clem., Anui I d
FIGURE S ACKNOWLEDGMENT
The author desires to express his appreciation to those who so generously gave permission to reproduce their photographs. Special thanks are due to the Eastman Kodak Company, Rochester, N. Y., both for permission to reproduce Figures 3 and 4, and for valuable information concerning treatment of glassware for photographing.
SELECTED REFERENCES
(1) L. J. HIBBERT,"A manual of photographic technique," I. Pitman & Sons, Ltd.. London. 1921.118 DD. (2) A. F. COLLINS,he amateur's photographi6 handbook." Thomas Y. Crowell Co., New York City, 1925, 362 pp. (3) E. J. WALL,"Photographic facts and formulas," American Photomohic Publishinn Co.. Boston. 1924. 386 DO. (4) EASTMA< KODAK COMPANY, "HOW to make good & m s , " 18th ed., Eastman Kodak Co., Rochester, N. Y . , 1933, 189 pp. (5) J. B. SCERIEVER AND T. H. C ~ I N O S "The , self-instructing
library of practical photography," Volume V, American School of Art and Photomaohv. Swanton.. Pa.. 1908. (Chapters 53 to 57. ante& &d&.',) WATKINS,"Photography," D. Van Nostrand Ca.. (6) ALFRED Inc., New York City, 1927,336 pp. (7) D "The comolete ohotomaoher." McClure . . R. C ~ L BAYLEY. Phiilios and '20.; New ~ o r kcity: 1906: 4i0 o ..i (Chapter . . 18, "Lantun slides.") E. BROWN."Photography," edited by GEORGE (8) L. P. CLERC, I. Pitman & Sons, Ltd., London, 1930, 566 pp.
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