Animals and Wild Nature.—The reflex camera is the only one with which satisfactory pictures can be obtained of animals at play, birds in the garden or in the woods, and wild nature generally. In this special field the benefits of visible focus and power to employ long-focus lenses react on one another. By the aid of the latter fair-sized pictures are possible at a distance sufficient to escape the observation of these nervous and bashful subjects.
Instantaneous Pictures.—Moving objects up to a certain speed come within the province of the ordinary stand camera, that is, if they can be focussed for in advance, and are bound to pass over a fixed spot, as, for instance, an express train, a coach, or, to a certain extent, the competitors in a cycle or motor race. The hand camera may by good luck succeed, if fitted with a reliable shutter. But the reflex camera is now recognised as the instrument fulfilling the conditions involved in the most satisfactory manner.
The one great problem involved in taking instantaneous photographs—and it applies to a less extent to those taken by the previously set-up stand camera—is the capacity of ensuring that the shutter shall act at the psychological moment ; for the best-devised shutter in the world takes a fraction of a second to respond to the press of the button. With an express train, a bird rising in flight, or a cricket bat, a very small error, say, - sec., may rob the plate of all value as a record. The personal equation comes into value here. Constant training of eye and nerve will create the faculty of anticipating, by just the right interval of time, the instant when the moving object will reach the most favourable point. After some practice this faculty will become automatic. Owing to the double character of the mechanism of a high-class reflex camera, in which the mirror catch has to act simultaneously with the shutter-release, the interval is probably rather longer, but none the less may be anticipated quite accurately by the individual.
The Shutter.—Diaphragm shutters, which for every other purpose are preferable, scarcely enter into competition with the focal-plane shutter for instantaneous work at high speed. With no other " back " shutter can one be quite sure that the two movements which control the raising of the mirror and the rapid exposure of the plate have been successfully accomplished. No other shutter has been brought to so
high a degree of efficiency during the last few years.
But beware of old-fashioned, second-hand, focal-plane shutters. Some are quite an inch away from the actual focal plane and create a sort of fog. And some operate with a jerk that may even affect the picture at low speeds, and will at any rate advertise the presence of the camera to every living thing within fifty yards. A cheap reflex with a cheap focal plane is worthless. To do good instantaneous work get one of the very latest patterns in which the multitude of cords, winders, hooks, and sliding knobs are done away with and, if possible, the tension springs as well. A single wind ing key should control all movements as in the old-fashioned Thornton Pickard shutter. Have the shutter tested for speeds at the earliest opportunity, to be sure that they are really attained by the instrument, or are purely arbitrary.
The intergearing of mirror and shutter should be such that when the mirror is shut up the shutter cannot be wound, and so expose the plate accidentally. Perhaps it is still better to demand a self-capping blind.
Our remarks about diaphragm shutters, however, require some modification. Since the time when this chapter was first written, two high-grade reflex cameras of great practical efficiency have been introduced, both equipped only with the diaphragm shutter, and one of them with the multi-speed shutter—probably the fastest in existence. But one great advantage of the focal plane remains still unchallenged, viz. that it permits of nearly double the amount of light reaching the plate in fast exposures with the lens at full aperture. There is a considerable loss of light with diaphragm shutters when working with a lens at any stop wider than f18.
Size of Camera.—The worst of a well-equipped reflex camera is the size and weight. It is a cumbersome article on a tour, even now that an excellent folding reflex is on the market. A quarter-plate camera is as large as can be managed by the ordinary man ; in fact we do not see why it will not serve for press purposes, seeing that an enlarge ment can be made as quickly as a contact print ; 5 x 4 in. is certainly the most formidable reflex camera that we should care to be burdened with, and its weight is half as much again as the quarter plate.