The pinhole & the modern camera

THE PINHOLE AND THE MODERN CAMERA WORK ESSENTIALLY THE SAME

A camera with a lens functions in the same way as a pinhole except that a much larger aperture is used with the lens camera. This larger aperture requires a means to get lightwaves to converge on a single plane. As you may know, when light travels through glass (or water) its direction changes. (This is called refraction, which is a bending of lightwaves.) By carefully engineering the curvature of the glass in a lens, lightwaves traveling through a wide aperture can be bent to simultaneously converge on a single plane, creating a "sharp" image. This is called focusing.

With lens cameras, only the objects in the plane of sharp focus are well defined; all other light is diffused. But, pinhole apertures admit such a very narrow selection of lightwaves that everything in the scene is equally in focus, without any help from engineered glass. The pinhole has unlimited depth of field.

PINHOLES NEED LONG EXPOSURE TIMES

Pinhole cameras have a universal focus (unlimited depth of field) for all distances from the camera but require long exposure times, since the volume of light entering the tiny opening is so small. Lens cameras utilize large apertures that let in lots of light, and therefore have very short exposure times that can be used to freeze action and create narrow zones of startlingly sharp focus.

The lens camera takes pictures involving movement superbly well, while pinhole cameras favor the still world. Pinholes also offer inexpensive access to a large variety of perspectives - they can "see" things in ways profoundly different from the human eye or the camera lens.

FOCUS RANGE OF THE PINHOLE IMAGE

One of the most striking characteristics of the pinhole image is its tremendous depth of field - accurate focus that extends throughout any distance in front of the camera. This characteristic offers a major advantage over lens cameras, which have selective focus, i.e. minimum and maximum focusing distance limitations.

The pinhole camera can be placed very close to a subject and the quality of focus will remain the same as for an object that is a hundred feet away. This remains true for cameras designed to "see" a wide-angle perspective, a telescopic perspective or anything in between. This feature accounts for much of the traditional interest artists have shown for pinhole cameras.

Various factors can influence image sharpness - movement and atmospheric haze, for example, which can cause an image to appear fuzzy.

QUALITY OF FOCUS

Notice weve used the phrase quality of focus. Lens cameras excel in producing a high quality of focus. Whatever is in focus is very sharp, considerably sharper than the vision achieved by the human eye. In the pinhole image, though, the field of focus is universal but the quality of focus is, at best, on par with the vision of the human eye.

PINHOLE SIZE DETERMINES QUALITY OF FOCUS

Pinhole images can be made to be fairly sharp or not sharp at all. There is an optimal pinhole size for every pinhole-to-film plane distance.

If the pinhole is too large for the distance, the image is soft. If the pinhole is too small, diffraction from the edges of the pinhole will degrade image quality. Many artists use pinhole cameras specifically to achieve a low quality of focus, which appears as soft, dreamy and enigmatic. It's a choice that pinhole photography offers artists - one that many like to have.