Fig. 58. 5 × 7 “Korona” Royal camera.
237. Choice of a camera. There is not a great deal of choice between the moderate-priced cameras of the various makers. A field camera is restricted to certain special uses, and hence is more serviceable when attachments useful only in portraiture or instantaneous work are absent. Even the ray filter, which has some value in the indoor photography of flowers, is useless in the field on account of the long exposure required. From considerable experience, “Premo” and “Korona” cameras have been found to be very satisfactory instruments. Doubtless the same statement would be found true of all the standard makes, but they have not been used by the writer. “Premo” cameras are made by the Rochester Optical Co., Rochester, N. Y., and “Korona” cameras by the Gundlach-Manhattan Optical Co., Rochester, N. Y. When two or more cameras are used, the best results can be obtained if they are of the same make, since the details of operation are then the same. The reduced liability of making a blunder is often offset by the fact that a different pattern will permit of a wider range of use. Any standard brand of plates will produce good negatives when skilfully used; at least, this has been proved in the case of the Cramer, Hammer, Seed, and Stanley brands. Every professional photographer has his favorite brand of plate, but the ecologist will do well to give the various kinds a thorough trial, and then to invariably use the one which gives him the best results. Thus, while it seems to be less popular with the profession than the others mentioned, the writer has obtained at least as satisfactory results with the Stanley plate as with the others, and consequently now uses it exclusively, since it is cheaper. The one important point is to make a final choice only after personal experience, and then to always use plates of the same brand, and preferably of the same rate of speed.
238. The use of the camera. To the ecologist, objects to be photographed fall into two categories, viz., those that move, and those that do not move. For practical purposes, areas sufficiently distant to render the movement imperceptible belong to the latter, as well as those, such as rock lichens, many fungi, etc., which can not be stirred by ordinary winds. The treatment accorded the two is essentially different. A fundamental rule of ecological photography is that detail must receive the first emphasis. The ecological view should be a picture as well as a map, however, but when one must be sacrificed, artistic effect must yield to clearness, and accuracy, i. e., technically speaking, contrast must give way to detail. Leaving apart the necessity of securing a sharp focus, which holds for all work, detail or definition depends directly upon the aperture of the diaphragm. Detail is increased by decreasing the size of the aperture. This in turn increases the length of time necessary for a proper exposure, and consequently the danger that the plant will be moved in the midst of the exposure. When the movement is negligible, the invariable rule should be to reduce the aperture to its smallest size, and to expose for a corresponding time. In all cases where the plants are close enough to show even a slight blurring on account of the action of the wind, the time of exposure must be reduced, in the hope that a short period of quiet will suffice for it. This reduction in time must be compensated by increasing the aperture of the diaphragm, and hence the amount of light which strikes the plate. The proper balance between the two is a matter of considerable nicety. It depends much upon the vagaries of the wind, and can readily be determined only after considerable experience. Although regions naturally differ somewhat in the nature of their winds, much experience in prairie and mountain regions warrants the primary rule that views of vegetation and plants subject to movement are not to be attempted on windy or cloudy days when it can possibly be avoided. Even on reconnaissance, a poor picture is no better than none at all, while in resident work a time will come sooner or later which will permit the making of a view satisfactory in all respects. There may be occasional instances when one is rewarded for keeping the camera trained on a particular spot for hours, and for wasting several plates in the hope that still moments will prove to be of the requisite duration. As a regular procedure, however, this has nothing to commend it.
Various methods have been tried to reduce or eliminate the trouble caused by the wind. Canvas screens have been used for this purpose with some benefit. When the picture is worth the trouble, a tent may be erected to afford a very efficient protection. This is too prodigal of time and energy, however, to be practicable under the usual conditions. Flashlight exposures on still nights are sometimes feasible, but the disadvantages connected with them are too great to bring them into general use. The best procedure is to bide one’s time, and to take quadrats, transects, and other detail areas, as well as many plant groups, at a time that promises to be most favorable. Single plants can often be moved in the field so that they are protected from the wind, or so that they are more strongly lighted. Slender, or feathery plants are usually very difficult to handle out of doors. The best plan is to photograph them in a room that is well and evenly lighted, or, best of all, in a stable, roomy tent.
239. The sequence of details. No photographer ever escapes blunders entirely. At the outset of his work, the ecologist must fully realize this, and accordingly plan a method of operating the camera which will reduce the chance of mistake to a minimum. The usual blunders which every one makes sooner or later, such as making two exposures on one plate, drawing the slide before closing the shutter, allowing the light to strike the plate through the slit in the holder, etc., can be all but absolutely avoided by a fixed order of doing things. This order will naturally not be the same for different persons; it is necessary merely that each have his own invariable sequence. The following one will serve as an illustration. As a preliminary, the plate-holders are filled, after having been carefully dusted, and the slides are uniformly replaced with the black edge inward. It is a wise precaution to again see that all the slides are in this position before leaving the dark room. This will ensure that a black edge outward always means that the plate has been exposed. The tripod is first set up and placed in what seems about the proper position. The camera is next attached to it, and the front and back opened. The bellows is pulled out, a short distance for views, and a longer one for detail pictures, and fastened. It is necessary to move the diaphragm index to the largest aperture and to open the shutter at “time.” The next steps are to orient the view or object, and to bring it into sharp focus upon the ground glass. The first is accomplished by moving the entire instrument, changing the position of the tripod legs, swinging the camera upon the tripod, or by raising or lowering the lens front. It is often desirable also to change the position of the object on the plate by use of the reversible back. In views with much distance, the foreground is brought into sharp focus. In close views, especially of quadrats, the swing is used to increase the distance for the foreground, and the focus is made upon the center. After focusing, the shutter is closed, the indicator set at the time desired, and the diaphragm “stopped down” as far as possible. Plate-holder 1 is slipped into place, care being taken not to move the camera by a sudden jar. The camera cloth is dropped above the holder and allowed to hang down over the slide end. The slide is drawn and put on top of the instrument, the black edge always up. The exposure is made and the slide replaced with the black edge outward. This point should receive the most critical attention, as a blunder here will often cause the loss of two negatives. The plate-holder is returned to the receptacle, or merely placed in the back of the camera, which is then closed. The number of the plate, the name of the view or object, the condition of the light, the length of exposure, and the aperture of the diaphragm, as well as the date, are recorded in a notebook for this purpose. The shutter is then opened at “time,” the diaphragm thrown wide open, and the front of the camera closed. When distances are short, the camera is often carried upon the tripod. As a rule, however, it is usually removed, and the tripod folded. In making subsequent pictures, the plates should always be used in their numerical order.
240. The time of exposure is obviously the most critical task in the manipulation of a camera. The time necessary for a proper exposure varies with the season, the hour, the condition of the sky, the light intensity of the formation, the color and size of the area to be photographed, and, finally, of course, with the aperture of the diaphragm. Fortunately for the ecologist, the variation in light intensity during the season, and even during the greater part of the day, is not great, and can ordinarily be ignored. The beginner will make the most progress by determining the exposure demanded by his instrument for taking a general view in full sunlight and with the smallest stop of the diaphragm. In standard cameras with lenses of ordinary rapidity, this is usually about one second. This will serve as a basis from which all other exposures may be reckoned until one has worked through a wide range of conditions and can recall just what time each view requires. On completely cloudy days the time required is five to ten times that necessary on a clear day; filmy clouds and haze necessitate an exposure of two or three seconds. The more open forest formations demand an exposure of about five to ten seconds on a sunny day, while the deeper ones require two or three times as long. A close view requires more time than a distant one, since the light-reflecting surface is much smaller. Quadrats require two or three seconds, and individual groups frequently take a longer time. The color of the vegetation plays an important part also: a dark green spruce forest requires twice as long an exposure as the aspen forest, and a grassland quadrat takes more time than one located in a gravel slide. In this connection, it is hardly necessary to point out that the lighted side of objects should always be taken, never the shaded one. The exposures indicated above are based upon the smallest stop. The reasons for using this whenever possible have already been given. When a larger stop is necessary, the exposure is decreased to correspond; for example, a quadrat that takes three to four seconds at 256 can be taken at 64 in one second. As a rule, the sun should not be in front of the camera, but, when necessary, views can be made in this position if the sun is prevented from shining directly into the lens.
241. Developing is as important as exposing. Indeed, it may well be considered more important, since a properly exposed plate may be spoiled in developing, while an under-exposure or over-exposure may be saved. Owing to the ease with which plants move in the wind, the ecologist is obliged to reconcile himself to many under-exposures, which can be converted into good negatives only by skilful developing. Every base station should have a good dark room, equipped with running water when possible, a good ruby lantern, and the proper trays and chemicals. Prepared developing solutions are alluring because of their convenience, but after an extended trial of several kinds, the writer has reached the conviction that pyrogallic acid, or “pyro,” is by far the most satisfactory in working with vegetation. Of almost innumerable formulae, the following gives excellent satisfaction and is convenient to use.
| I. | II. | ||
|---|---|---|---|
| 500 | cc. water | 500 | cc. water |
| 30 | grams sodium sulphite | 5 | grams pyrogallic acid |
| 30 | grams sodium carbonate | ||
For developing, equal parts of I and II are mixed, and a few drops of a 10 per cent solution of potassium bromide added, unless there is reason to suspect that the plate has been seriously underexposed. The fixing bath is a concentrated solution of sodium hyposulphite, “hypo,” to which a few drops of acetic acid are added. It should be replaced every week or two, depending upon how much it is used. A tray of water is kept at hand for bringing out the detail in underexposed negatives, and a second tray is used for washing. The “pyro” and the bromide solution should always be within reach, the former for accelerating, and the latter for retarding the development of unsatisfactory plates.
The image will begin to show on a properly exposed plate within one to three minutes after it has been put in the developer. If the image appears almost instantly, and then recedes quickly, the plate is badly overexposed, and should be thrown away. In case it “comes up” less quickly, indicating that it is not greatly overexposed, it can be saved by the addition of more bromide. When the image does not show till the end of five to ten minutes, the plate has been underexposed. It is then necessary to add more “pyro,” taking care not to pour it on the plate, and, after the image appears with its striking contrast, to leave the plate in water until as much detail as possible is brought out in the shadows. In the case of a normal exposure, when greater detail is desired, the negative is left for some time in water, and when contrast is sought more “pyro” is used. Negatives with unusual detail lack “snap”; they are “flat,” and fail to make artistic pictures. Contrast, on the other hand, often obscures detail, and the best results can only be obtained by a happy combination of the two. The most important maxim in developing is that the process shall be continued until the image has become indistinct. The universal tendency of the beginner is to remove the negative the moment the outlines grow dimmer, and the result is a thin, lifeless negative. It is almost impossible to develop too far, if the image is not allowed to disappear. Negatives of this sort are “thick,” and though they print more slowly, produce brilliant pictures. A large quantity of the developing solution is used with single plates in small trays, and is allowed to act without rocking the tray. Much time is saved, however, by developing several plates together, and to avoid using a large quantity of the solution, the tray is gently rocked from time to time. This movement is particularly necessary at the beginning, in order that the plates may be covered evenly, and at once. Fifty cubic centimeters of the solution will develop three or four 6½ × 8½ plates, and twice as many 4 × 5’s. After the developer has once been used, it is kept for several days to restrain overexposed plates. As soon as the plate is developed, it is rinsed in water, and placed in the fixing fluid, until the white opaqueness is entirely removed. The “hypo” is then washed out by immersing the negatives for one to two hours in running water. If the latter can not be secured, the water in which they are placed should be changed frequently. The negatives are then air-dried within doors, in a place free from dust. Finally, they are filed away in negative envelopes, each bearing the name and number of the negative, and preferably also, the time and other exposure data.