Seeing and Believing
The distortions apparent in this Jacques Henri Lartigue photograph stem from two things. First, the design of the vertical traveling slit shutter exposes the top of the frame before the bottom, causing the top of the wheel to be exposed before the bottom. Second, Lartigue was apparently panning the camera to track the motion at a rate slightly faster than the car was actually going—so the wheel appears to stretch behind the car. The spectators were stationary, and appear to lean backward due to the change in camera position during the exposure. Photographic evidence like this, read without any understanding of the camera’s mechanisms, tend to produce some pretty strange conclusions regarding motion.
I am impressed by the strength of the conviction that the top of a wheel moves faster than the bottom in some late 19th and early 20th century accounts. Lartigue’s visual trick doesn’t appear to be that unique. Though Martin Aldur doesn’t assert that such a view is “true,” he does assume that it is accurate:
I remember seeing a photograph of a racing motor car taken with a shutter that was not sufficiently rapid for such a subject—thereby approaching more nearly the condition of human sight—which showed these two causes at work, for the spokes and rims of the wheels were distinct and exact where the tyre touched the road, but blurred and pulled forward at the top where they were advancing more rapidly.
The duty of the spokes, which are the legs of the machine, is to thrust the axle forward, just as the foot and leg thrust the horse forward. We are so inclined to watch the horse as it gallops that we think of it as swinging its legs to and fro past the indistinct landscape; we do not see the hoof stationary upon the ground propelling the creature forwards. Yet this is what actually occurs, and affects our impressions, so that as man or animal runs or leaps, fights or dances, a tail, a sword, a piece of drapery, a foot, a hand will sometimes seem to hover or lag behind, and make the limb appear too long, so that the artist in his truth to his impression will be led insensibly to see and use such accurate “inaccuracies” upon which the exact effect depends—inaccuracies as true as that colour is modified by the colour that is placed against it, or that a white flagstaff, which looks light against a house, looks darker and thinner where it comes against the evening sky above it, and must be so painted to give the effect, although we know it to be actually of the same tone throughout its length. And so it is not only for the pattern of the picture that the leg which is too long in Rubens, the limb which is “deformed” in Degas are right, but also in truth to the natural appearance for those who can see.
An artist to whom such changes are always evident will necessarily introduce them into his work, either so subtly as to pass unperceived by most people or so frankly as to shock and distract some spectators.
From “The Representation of Movement in Art” by Martin Aldur The Burlington Magazine for Connoisseurs, Vol. 23, No. 124 (Jul., 1913), 204-207.