Part 2

The “convertible” lenses of various makers are also separable, and where the rear and front lenses are of different foci three focal lengths are obtainable. These lenses are of the highest grade, and consequently expensive. In a bright light, or where great speed is not required, they do not seem to be as superior to the trade lens as the much higher price would lead one to expect. But in dull days, or in the shadow, or where extremely rapid exposures are necessary, their superior qualities become evident. My experience with these convertible lenses has been limited to the Zeiss Anastigmat, Series VII _a_, of which I am now using a No. 10 with a combined focus of eight inches, the front and rear lenses both having a focal length of fourteen inches. This combination is preferred to one in which the component lenses are of different foci, because of the greater speed of the two when combined, and furthermore, because, being of the same focus, they could, if occasion arose, be used in a twin-lens box. The speed of the combination is registered at F. 6.3; that of the single lenses at 12.5. With the former the most rapid exposures can be made successfully, while the latter are sufficiently fast to permit of ordinary instantaneous work. This lens is stated to cover a 5 × 8½ plate, and when in use on a 4 × 5 camera gives a high degree of illumination and perfect definition.

The telephoto lens may be employed in certain kinds of bird photography with not unsatisfactory results. Its disadvantages are lack of speed, an exposure of at least one half a second to a second being required at F. 8 in bright sunlight, the necessity of extreme care in focusing, and of absolute rigidity of the camera at the time of making the exposure. In short, the telephotographer needs more time, both before and after pressing his bulb, than the bird photographer is often accorded. However, with such subjects as nests high in trees or on cliffs, Herons and other shore-inhabiting birds, Ducks on the water or Hawks perched in leafless trees, the telephoto will be found serviceable.

Negatives are frequently secured in which the figure of the bird, while small, is sharp, when, by enlargement, a desirable picture can be made of what in the original was too small to be easily distinguishable. An increase in size of two diameters is possible from any fairly sharp negative, but if the object be in perfect focus an increase of four diameters may be made.

These enlargements may be made with an enlarging camera or with the aid of a Nehring enlarging lens, which is placed between the front and back lenses of the view lens, when, with the ordinary long-focus camera, a magnification of about four diameters may be obtained, the image being thrown on to a piece of bromide paper in the plate holder.

Through enlargement many apparently worthless negatives become of value, and in some instances pictures can be made from different parts of the same negative. From the sportsman-photographer’s standpoint there is, however, one objection to the use of a magnifying lens. It gives deceptive results, and those who are not familiar with its powers are apt to accord the photographer undue praise for his apparent skill in successfully approaching some bird or beast which may have been far out of range. A not wholly unrelated kind of enlargement is sometimes applied to the contents of creels and game bags!

But the animal photographer is so heavily handicapped that in this case the end assuredly justifies the means. As a matter of information, however, it seems eminently desirable to accompany all enlarged pictures by a statement of the extent of their magnification, and throughout this book this plan is followed. Consequently, when there is no mention of enlargement, it may be accepted as a fact that the print from which the reproduction was made was obtained from the negative by contact.

In illustration of these suggestions in regard to the proper lenses for bird photography, a series of pictures is presented which shows the results to be obtained under the same conditions with different lenses.

[Illustration: 2. Lens Test No. 1. Mounted Flicker on fence post, distance fifty feet. Eight-inch focus, Zeiss Convertible, No. 10, Series VII _a_ lens; diaphragm F. 8, ¹⁄₂₅ second; Cramer “Crown” plate. Photographed at noon, in sunlight, November 30, 1899.]

[Illustration: 3. The bird in Test No. 1 enlarged about three diameters.]

Placing a mounted Flicker (_Colaptes auratus_) on a fence post, and setting up my tripod at a measured distance of fifty feet, a series of test exposures was made, of which three are presented as follows: First,^2 eight-inch lens (Zeiss Convertible Series VII _a_, No. 10), stop F. 8, time ¹⁄₂₅ second; second,^4 fourteen-inch front lens of the combination, stop F. 16 (equivalent to F. 4 of the eight-inch); third,^6 telephoto attachment with eight-inch lens, twenty-one-inch bellows, stop F. 8 of the eight-inch, time one second. Commenting on the results of these tests it may first be mentioned that in the “Unicum” shutter employed exposures of a so-called “¹⁄₁₀₀” and “¹⁄₂₅” seconds gave exactly the same results both with the combined eight-inch lens and the front fourteen-inch lens; the actual time, however, was doubtless not far from ¹⁄₂₅ of a second. The negatives, therefore, show, in the first place, that the long-focus lens is capable of doing fairly rapid work. Continuing our comparison, we observe that the eight-inch gives a fairly wide field, excellent depth of focus, but a very small image of the bird, for which alone the picture has been made. With the fourteen-inch we decrease the extent of the field nearly one half and almost double the size of the object pictured. This, however, has been done at the loss of depth of focus, not even the first of the line of posts running directly into the background being sharply defined, while with the eight-inch all are in focus.

[Illustration: 4. Lens Test No. 2. Same subject, distance, plate, and date as Test No. 1. Front lens (fourteen-inch focus) of Zeiss Convertible, No. 10; diaphragm F. 16; ¹⁄₂₅ second.]

[Illustration: 5. The bird in Test No. 2 enlarged about three diameters.]

The telephoto gives an enlargement of about six diameters of the image thrown by eight-inch lens, and three diameters increase of that of the fourteen-inch lens. It practically restricts the picture to the immediate surroundings of the bird, and is without focal depth.

[Illustration: 6. Lens Test No. 3. Same subject, distance, plate, and date as Tests Nos. 2 and 3. Eight-inch Zeiss Convertible, Series VII _a_, No. 10, with telephoto attachment; diaphragm F. 8; twenty-one-inch bellows; one second (½ second was later found to be full time).]

Having now made three good negatives in the field, we may, by enlargement, improve on the image of the bird obtained. The possibilities in this direction are clearly shown by the three enlargements accompanying the contact prints from their respective negatives. In each instance the enlargement is about three diameters, and the telephoto negative of course furnishes the most satisfactory picture. When the difficulties of telephotography are considered, however, and the ¹⁄₂₅-second exposure of the fourteen-inch lens, which permits of hand work, is compared with the one second of the telephoto, we believe that for general work in photographing birds a lens having a focal length of at least fourteen inches will be found the most satisfactory. It should be added that, in order to make them wholly comparable, the three contact prints as well as the enlargements were made on enameled bromide paper.

[Illustration: 7. The bird in Test No. 3 enlarged about three diameters.]

_The Shutter._—For fairly rapid, slow, and time exposures, a lens shutter, such as is sold with trade cameras, will be found suitable. Simplicity and noiselessness are the chief requirements in this kind of a shutter. The “Iris Diaphragm” shutter is noiseless when used for slow exposures of two or three seconds, a matter of much importance in making time pictures of sitting birds, who are apt to turn their head if they hear the click of the shutter. This shutter, however, does not respond quickly in slow exposures and is very heavy, a disadvantage in telephotography.

The “Unicum” shutter is lighter, responds quickly, has a lever to which a thread may be attached for making exposures from a distance, can be easily diaphragmed from the rear, but is not wholly noiseless. There are also other shutters, each possessing good points of its own, and the selection of any one of them for use in medium rapid, slow, or time work can be left to the photographer, who should, however, remember that the time scales on these shutters represent degrees of difference and not exact measurements of time, and that there is great variation in the exposures of different shutters of the same make when similarly adjusted. Thus the “one fifth of a second” of one shutter may be equivalent to the “one second” of another. The scale on most of these shutters calls for a speed not exceeding a ¹⁄₁₀₀ part of a second, but this is far too slow an exposure to successfully photograph a flying bird at short range where a speed of at least ¹⁄₅₀₀ of a second is required.

For very rapid work the choice is limited to one kind of shutter—that is, the focal-plane, which in effect is a curtain with an adjustable slit which is placed directly in front of the plate. Great speed with this shutter is in part secured by increasing the tension of the spring, which acts as its motive power, but more particularly by decreasing the width of the slit. Assuming, therefore, that it takes one second for the slit to pass from top to bottom of a plate four inches high, and that the slit is one inch in width, it follows that each portion of the plate is exposed to the light for a quarter of a second. Decreasing the width of the slit one half, proportionally reduces the time of the exposure, and by this means, in connection with an increase in the speed with which the curtain is moved, an exposure of ¹⁄₁₀₀₀ of a second is possible.

In addition to possessing the advantage of great speed, this shutter also passes a higher percentage of light than a lens shutter even when the actual time of the so-called exposure is the same. This is due to the fact that the lens opening is in no way affected, it being the same throughout the exposure. With a lens shutter, on the contrary, the full value of the opening is given for only a fractional part of the exposure, the parts of the shutter more or less filling the opening during the rest of the time. With a focal-plane shutter, therefore, one may do rapid work under conditions where a lens shutter could not be successfully employed; time exposures, however, can not be made with the focal-plane shutter, and for all-around work the camera should be fitted with both a lens and a focal-plane shutter.

The reflecting camera, as before stated, is fitted with a focal-plane shutter, and, as described, it is released by pressing the lever, which raises the mirror. Lens shutters, however, are released by a pneumatic bulb, or in some cases by a thread or string. When the exposure is to be made from a distance as much as one hundred feet of tubing may be employed. With any length of over twenty-five feet an extra large bulb is required. The ordinary tubing sold by photographers will not be found so well adapted to long-distance work as a less elastic kind, which does not so readily yield to pressure and transmits a larger portion of the force applied when squeezing the bulb.

_The Tripod._—A stout two-length tripod is to be preferred to one of the slender multifolding type, in which stability is sacrificed to weight and size. The legs, except the inner sides of the upper section into which the lower section slides, and brass work should be painted bark color in order to make them as inconspicuous as possible. For use in the water a metal tripod will prove more serviceable than one of wood.

A very useful substitute for a tripod is the “Graphic” ball-and-socket clamp designed more especially for bicycle camerists. With it a camera can easily be attached to the limb of a tree, rung of a ladder, or, by screwing a block on to the head of the tripod, it may be employed in connection with the tripod—in fact its applicability will be evident to every one using it.

_Plates._—Among the many excellent brands of plates now offered to photographers there is really very little difference. However, it is advisable to select the one you think the most rapid and use it to the exclusion of all others. Under certain circumstances—in photographing Robins, for instance—isochromatic plates will be found desirable, and where a strong head light can not be avoided nonhalation plates may be employed.

So much industry, skill, and patience are generally required of the bird photographer before he makes an exposure that he should guard against all chances of failure from the photographic side. It is therefore advisable to thoroughly test plates which it is probable may be exposed on a very difficult subject. Under no circumstances should the plate holders be needlessly exposed to the light, and when the camera is to be left for an indefinite period with the slide drawn from the holder and plate ready to expose, it should be carefully wrapped in the dark-cloth.

_Blinds._—As the sportsman constructs blinds in which he may conceal himself from his prey, so the bird photographer may employ various means of hiding from his subjects. The Keartons recommend an artificial tree trunk for use in wooded places and an artificial rubbish heap for open fields. The former may be made of light duck, painted to resemble bark, and placed over a frame.

The frame of the Keartons’ is of bamboo, but I find white pine answers very well, the main things to be considered being lightness and portability. The frame should therefore be collapsible in order that it may be easily packed.

The Keartons’ field blind or “rubbish heap” consists of an umbrella, to each of the ribs of which strips of bamboo four feet in length are tied. This is then covered with light brown holland and wisps of straw tied over it in such a way as to “virtually thatch the whole structure.” Doubtless cornstalks properly arranged would make an excellent field blind.

It is difficult to carry one of these blinds in addition to a camera, etc., without assistance, and I fear that the inconvenience attending their use will restrict them to the few enthusiasts who count neither time, labor, nor cost in attaining a desired end.

For my own part, I prefer, when possible, to conceal my camera and make the exposure from a distance rather than to weight myself with a portable blind and to endure the discomforts of being confined within it.

_Sundries._—The bird photographer will find that he requires numerous articles not usually to be found in the regulation photographic outfit, as, for example, climbers for ascending trees and stout cords for hauling the camera up after him; a dark-cloth, green in color, to aid in disguising the camera, and a mirror. The latter should be of plate glass, and measure at least twelve by ten inches. A good plan is to buy a piece of glass of desired size and frame it simply in white pine. It may then be attached to a limb, a stick driven in the ground, or other convenient object, by means of the ball-and-socket clamp mentioned under Tripods, which may be screwed into the back or the outer border of the frame. Such a mirror will reflect sunlight many yards to shaded nests, where, in photographing old or young birds, a quick exposure is necessary. A vest-pocket mirror, for use in reflecting the reading of the diaphragms or time on the shutter, will permit one to make the desired changes from the rear, and thus prove helpful when conditions do not permit one to work in front of the camera.

A device which might be arranged on the principle of a trap, the trigger to be sprung and exposure made when the bait is taken, would doubtless capture some interesting pictures. An apparatus connected with an automatically fired flash-light, has been employed by Mr. G. A. Shiras, of Pittsburg, in photographing deer at night, with phenomenal success. The connection with the camera shutter was so made that the deer, in walking, touched a cord which exploded the flash-light, and, at the same moment, made the exposure. The light weight of most birds, however, requires a much more delicate apparatus, while an even greater difficulty is found in the movement caused by the release of the trigger, which startles the bird just as the exposure is made.

Thus far in my experiments I have been unable to overcome these objections, but I trust some other bird photographer will be more successful.

Those who are ambitious in the direction of cliff photography I would refer to the Keartons’ admirable treatise on the subject in their Wild Life at Home, for a description of the paraphernalia needed and the manner in which it should be used. My own experience in this line is limited, and I confess to the utter absence of a desire to increase it!

THE METHODS OF THE BIRD PHOTOGRAPHER

Claiming no special knowledge of the technique of pure photography, I would refer the beginner to any of the several excellent books designed to explain the rudiments of optical and chemical photography, and to instruct in regard to the matters of exposing, developing, printing, etc. Only such suggestions are given here, therefore, as relate directly to the manner in which birds, their nests, eggs, and haunts may be photographed.

_Haunts._—Photographs of the characteristic haunts of birds should show not alone general topography, but should also be made with special reference to the bird’s feeding habits, which, more than anything else, govern the nature of the locality selected. Thus, a photograph of the home of the Woodcock would have added value if, in the immediate foreground, the “borings” made by this bird in probing the earth for food were evident; or a marsh scene, in which wild rice was conspicuous, would tell something of both the haunts and the food habits of the Reedbird and Red-winged Blackbird in August and September. In a similar way, pictures of wild cherry and dogwood trees, of bayberries and red cedar, which show both fruit and surroundings, are of interest in connection with the biographies of many birds.

[Illustration: 8. Spring.]

[Illustration: 9. Summer.]

_Seasons._—The camera permits us to make so exact a record of the rise and fall of the year, as it is registered by vegetation, that we can actually compare existing conditions with those which prevailed at any previous time. Compare, for example, the series of four pictures^{8–11} here presented, all made from the same point of view, in order to appreciate how graphically seasonal changes may be shown by the camera. In this instance, photography is of more service to the botanist than to the ornithologist; but every student of migration knows how closely related are the appearance of certain birds and flowers, and will readily appreciate, therefore, the value of a series of photographs of several different subjects, taken at short intervals, and showing the changes in vegetation due to the approach of summer or winter. In connection with such related phenomena as temperature, rainfall, and weather, these pictures form as accurate a record of the seasons as it is possible to make, and if data of this kind could be brought together from many selected localities, we should have an admirable basis for the intelligent study of certain phases of bird migration.

[Illustration: 10. Autumn.]

_Nests and Eggs_.—The photographing of nests is one of the simpler forms of bird photography, but in many instances success is achieved only through the exercise of much patience and ingenuity.

[Illustration: 11. Winter.]

It should constantly be borne in mind, in photographing nests, that what is desired is not so much a picture of the nest alone as one which shows it in relation to its environment—in short, a picture of the nesting site is of more value than one of the nest only. It is advisable, however, to make at least three pictures, two^{12, 13} of which shall show the nature of the locality chosen, the other^{14} the character of the nest and its immediate surroundings. When the nest is not above five feet from the ground, little difficulty will be experienced in securing the desired picture. When on the ground it will sometimes be found helpful to put what naturally would be the rear leg of the tripod forward, _between_ the other two, when it will serve as a brace from in front, and permit the camera to be tilted well downward without danger of its falling.

Nests at an elevation of seven or eight feet, in saplings, may be photographed by lengthening the tripod with short legs, each supplied with two staples or collars into which the ends of the tripod may be slipped; or a ladder or light scaffolding will sometimes be found necessary.

[Illustration: 12. To show nest locality of: 1, Tree Swallow; 2, American Bittern; 3, Song Sparrow; 4, Maryland Yellow-throat; 5, Marsh Hawk, of which nesting site, nest, and young are shown in the two following pictures, Nos. 13 and 14. Meridian, N. Y., June 8, 1898.]

For photographing nests in trees the “Graphic” ball-and-socket clamp is of great assistance. With it the camera may be attached to a limb, or, if the limb is too large, a block may be nailed to it, thus furnishing a grip to which the clamp may be fastened.

[Illustration: 13. Nesting site, nest, and young of Marsh Hawk.]

Nests should be photographed from the side, but eggs should be photographed from above in order to show their position in the nest as they were arranged by the incubating bird. The nest should therefore never be tipped, nor should the eggs be touched, lest the value of the subject be destroyed. The markings of most birds’ eggs are already well known, but if photographs of them are desired they can be made from the thousands of eggshells with which ill-directed effort has stocked the cabinets of misguided oölogists.

[Illustration: 14. Young Marsh Hawks and nest.]

It is not advisable to make photographs of nests in the sunlight, a diffused light giving greater detail. A screen of some thin white material should therefore be used as a shade when photographing nests exposed to the direct rays of the sun. This, however, will not be found necessary if the picture be made within two or three hours after sunrise, when the light is soft and the foliage comparatively motionless, permitting the use of a small diaphragm and a long exposure.

[Illustration: 15. Young Great-crested Flycatcher.]

_Young Birds._—The ease with which photographs of young birds may often be secured, the fact that with the camera their appearance and development may be more satisfactorily recorded than in any other way, makes their study by the photographer of exceeding importance. Photographs of young birds should of course be accompanied by notes on food, calls, special actions, etc., which the camera can not well portray.