The art of photography was born in controversy, a contest of sorts between two perpetual rivals, the English and the French. It all started in the mid-eighteenth century when a team of German scientist discovered that a certain form of silver crystals were chemically sensitive to light. These silver crystals would actually change their chemical composition and “clump” together dependant to the intensity of the light they were exposed to.
This discovery did not meet with that great of public interest, probably because there was no clear use for darkening silver with the sun. But in the first decades of the 19th century two men seemed to have the same idea simultaneously (or that is at least how some historians have recorded it.) Both Nicephone Niepce and William Talbot had for some time been interested in optical effects of an old contraption known as the “camera obscura.” The camera obscura has a long history. It was one of the many devices chronicled in the notebooks of Leonardo Da Vinci. The word camera means literally “dark box,” and the camera obscura was essentially that: a dark box with the addition of a small opening, or aperture.
The effect of the camera obscura is a product of the dynamic nature of light. Sunlight travels in waves across the solar system, and like waves of water, pours into openings as it passes through. The aperture on the camera is just such an opening. Inside the camera a mirrored image of the world outside is projected, albeit upside down and backwards, on the back panel of the box. It is a fairly marvelous effect: a mirror of the world projecting into the darkness.
Artists had for centuries used the camera obscura as a tool for drafting and to assist in rendering realistic perspectives. What Talbot and Niepce did that revolutionized the use of the camera was to experiment once again with the light sensitive qualities of silver. In the beginning the whole endeavor was long and cumbersome, but amazingly it worked. By focusing the image coming through the aperture onto a chemically treated silver plate one could “fix” that image into something permanent. With this, the photographic age began.
The essential physics of photography did not change until the digital revolution effectively took silver out of the mix. For over one hundred and sixty years the craft of photography involved the simple basics of a dark box (the camera), an aperture that eventually evolved into assortment of lenses to better focus the image, and a shutter to control the duration of time the aperture would remain open. These are the tools of the trade.
Breaking photographic technique down to these basics makes it easier to understand the technical choices and compromises we make in creating a photograph. The key to technical photography is understanding how to balance the size of the lens opening, the aperture, with the duration of time it remains open, the shutter speed. These two elements combine to create the “exposure,” which accounts for the amount of light exposed onto the film. One way of viewing the balance between the shutter and the aperture is the idea of a manual scale. Whatever you do to one side has an equivalent effect on the other. What you are attempting in creating a technically proficient photograph is to find the perfect balance on the scale.
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