Photomicrography, << `foh` toh my KROG ruh fee, >> is the technique of taking magnified photographs of small objects. The technique can be used to investigate the nature of substances in many branches of science, including biology, forensic science, geology, medicine, and metallurgy. The photographs are most often taken through a microscope. But cameras with special lenses can capture images of lower magnification.
Originally, researchers who needed a permanent record of images seen through a microscope had to draw them by hand. Soon after the development of photography, photographers found ways of fitting a camera to a microscope. They could then record microscopic images more quickly and with greater accuracy.
For the highest magnification, a camera body is attached to the top of a microscope. Most often, the camera body serves simply as a holder for the film. All the necessary controls, and systems for illuminating and viewing the object, are built into the microscope. The object is illuminated from the front if it is opaque. Transparent objects can be illuminated from behind. The photographer can use colored lighting or a filter to help highlight important details.
In some cases, a camera with a lens attached is mounted on a microscope. The photographer can then control the amount of light entering the camera by adjusting a part of the lens system called the diaphragm. The diaphragm setting also determines the depth of field—that is, the range of distances over which the object will be in focus.
The best equipment produces photographs with useful magnifications of up to about 700 times, the highest magnification possible with an optical microscope. Further enlargement will not reveal any more detail. The image can be captured on photographic film or on a charge-coupled device (CCD), a light-sensitive component in a digital camera.
See also Camera ; Microscope .
