PHOTOGRAPHING MOVING OBJECTS.
In most instances where the beginner attempts the photographing of moving objects, the result will be disappointing, this is due solely to his lack of appreciation of the circumstances and the actual conditions confronting him. For example, he takes his camera to the race track to photograph a friendly brush between local trotters.
Securing a position just under the wire he waits for the finish, and as the horses rush by at a 2.10 clip he snaps them broadside from a distance of ten feet, and fails to understand why the negative should show nothing but a blur, for he will have nothing else. The reason for his failure is this ; if he has a double lens instrument with an F. P. K. automatic shutter it has worked in approximately of a second, an apparently very short space of time, but we find on figuring it out that a horse covering a mile in 2.10 covers 4o feet and S inches in one second of time or over nine inches in of a second, the time the shutter is open—a sufficient distance to make a most decided blur. The distance the image will move on the plate during exposure is to the distance the object moves, as the focal length of the lens is to the distance from lens to object. In this case we will suppose the focus of the lens to be six inches, and we know the distance from lens to object to be ten feet (12o inches) and the distance the object moves approximately nine inches. We will let X stand for distance image moves on plate and it gives us the following equation : X : 9 : : 6 : 20 = It is obvious that if the object moves of an inch on the plate the picture will be ruined. We find then that in order to take pictures of moving
objects at right angles there are two factors of prime importance—the speed of the shutter and the distance from the object. In the ordinary amateur outfit the shutter speed cannot be materially increased and we must there fore take the picture from further away. Experiment has proven that in order to successfully take pictures of rapidly moving horses, etc., from a position near by and at right angles the shutter must work in from to INV of a second (Muybridge claimed to have used a shutter working in of a second) and this extreme speed necessitates a special camera and lens as well as a special shutter.* But there are tricks in all trades and satisfactory pictures of rapidly moving objects can be readily made by photographing them from partly in front as well as from a reasonable distance. The accompanying picture of the Empire State Express, moving at full speed, shows plainly what can be done in this direction. It IA as made with a Pocket Kodak and is a good illustration of what can be accom plished by taking the picture from a point at a considerable distance from the object and also somewhat ahead of it. By acting on this hint the amateur can soon learn to take pictures of rapidly moving objects, and in such a manner as to largely avoid the disagreeable blurring.