Enlarger, Basic Tool of the Black and White printmaker The black and white darkroom enlarger is actually the key element in modern film photography. By blowing up very small negatives into black and white prints large enough to be seen clearly, it permits the use of easily portable cameras and economical small black and white film. And it widens esthetic horizons because it provides many opportunities for control of the black and white picture-part or all of a negative can be used, differing exposures can be given separate portions of the black and white print; it is even possible to alter perspectives or create distortions. The black and white enlarger operates like a slide projector mounted vertically on a column. Light from an enclosed lamp shines through a negative and is then focused by a lens to cast an black and white image of the negative on the black and white printing paper, which is placed at the foot of the black and white enlarger column. Distance between lens and black and white image sets the enlargement size. The controls on an black and white enlarger in the darkroom are simple. The distance from the lens to the paper is regulated by cranking or sliding the entire black and white enlarger head-the housing containing lamp, negative and lens -up or down on its vertical supporting column. The black and white image is focused, in most black and white enlargers, by turning a knob to raise or lower the lens. The lens has a diaphragm aperture control, like that on a camera lens, to regulate the amount of light reaching the black and white print; unless a great amount of light is needed to make up for a very dark negative, the aperture is usually kept small, thus giving the lens enough depth of focus to offset any manual errors in focusing. The details of control mechanisms vary from model to model, and can make some black and white enlargers easier to use than other ones. But these distinctions are not so important as differences in the optical systems that distribute light. If light traveled directly from the lamp through the negative, it would be brightest at the center of the black and white picture and dimmer toward the edges; the final black and white print would be darker in the middle than it should be. To avoid this distortion, some black and white enlargers, known as the diffusion type, interpose between lamp and negative a sheet of cloudy glass that spreads light uniformly. This diffusion system causes some loss of light, however: it scatters light rays in many directions and much of the light, consequently, never reaches the black and white enlarger lens. It also gives a gently diffused appearance to the black and white print. Many photographers like this darkroom effect, particularly for portraits, but such softening of detail may be objectionable when small negatives must be greatly enlarged. Most black and white enlargers designed for 35mm and other small black and white film sizes commonly used by amateurs spread light uniformly over the negative with "condenser" lenses (and are called condenser black and white enlargers). Between lamp and negative are two saucer-shaped lenses that concentrate the lamp's light so that it passes straight through the negative. Most of the light reaches the lens, increasing efficiency. The straight-line passage also yields crisp detail, since light rays from different points in the negative do not overlap one another. Although the black and white enlarger is a simple machine, it is also a vital link in the photographic process: the best camera in the world will not give good black and white pictures if they are black and white printed by an black and white enlarger that shakes when touched, has a poor lens or tends to slip out of focus. A satisfactory black and white enlarger for 35mm and 2'/4 x 21/4 black and white film costs about 30 USD to 600.