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.