Eastman Kodak Camera

It is called simply "Camera". The claims cover the shutter and lens support and the film-handling mechanism — the roll film chemistry is separate work.

Write it out: plates, collodion, silver bath, developer, fixer, water, a dark tent. That inventory is the problem being solved, and it is not an optical one.

Make a simple wooden box with a lens aperture at one end and a film plane at the other. Every joint must be light-tight; test it in sunlight with film-free paper inside.

Set the lens at the hyperfocal distance and glue it there. With a small aperture, everything from a couple of metres to infinity is acceptably sharp — and there is nothing for the user to get wrong.

Depth of field grows as the aperture shrinks. A small stop buys you a camera with no focusing control at the price of needing brighter light and faster film.

Make a spring-driven disc with a slot that sweeps past the aperture once. One speed, one control — no exposure decisions are delegated to the customer.

Mount a supply spool and a take-up spool with a key. The original held a hundred exposures — enough that reloading is somebody else's job.

Fit a mechanism that advances one frame and stops. Without it users double-expose, and a double exposure is a complaint the company must answer.

Make it impossible to fire twice without winding. Design out the error rather than instructing against it — that principle is the whole product philosophy.

Prepare a silver halide gelatin emulsion on a flexible base. Gelatin dry plates, unlike wet collodion, can be coated in advance and stored — that is what makes roll film possible at all.

Glass gives a better negative and cannot be rolled. Roll film is optically worse and enables a hundred exposures in a pocket — the worse technology wins on system grounds.

Point and press, a dozen times, in daylight. No focus, no aperture, no speed. Note how many decisions have been removed from you.

Process it and look at what went wrong: motion blur, subjects too close, dim interiors. Those are the residual limits of a one-control camera, and they are predictable.

Tally what Rochester did instead: develop, print, reload, return. The camera is one component of a service, and the service is the actual invention.

The patent. US 388,850, "Camera", granted 4 September 1888 to George Eastman of Rochester, New York. The Kodak sold that year for 25 dollars loaded with a roll of a hundred exposures. When the roll was finished the entire camera went back to Rochester; ten dollars bought developing, printing and a reloaded camera returned. Eastman coined the name Kodak himself, wanting a short, strong word that meant nothing in any language and could not be mispronounced.

The chemistry came first and is the real foundation. Wet collodion plates had to be coated, exposed and developed within about fifteen minutes, so a darkroom travelled with the camera. Richard Leach Maddox's gelatin dry plate of 1871 broke that constraint: a gelatin silver halide emulsion could be coated, dried, stored and developed later. Eastman began by manufacturing dry plates in 1880, then put the emulsion on flexible roll material. Without the dry emulsion there is no roll film, and without roll film there is no snapshot.

Every design choice removes a decision. Fixed focus at the hyperfocal distance with a small aperture means nothing to focus. A single shutter speed means nothing to set. A hundred-exposure roll means nothing to reload. An interlock between wind and shutter means double exposure is impossible rather than merely discouraged. Each of these makes the camera optically worse than a contemporary plate camera and makes it usable by someone with no training — and the wind-shutter interlock is a small classic of designing the error out instead of writing a warning about it.

The film was also worse, and that was fine. A glass plate gives a sharper, flatter negative than early roll film, which was thinner, curled and less stable. Roll film won because a hundred exposures fit in a pocket and glass does not, which is a recurring pattern: the component that is worse in isolation wins because it makes the SYSTEM possible. Kodak went on to dominate photography for a century, and the same company's difficulty in abandoning film for digital a hundred years later is a well-documented sequel to this patent.