Exposure - exposure during photographing a certain amount of light on light-sensitive layer of photographic material through the open gate in front of window unit personnel. The shutter of the camera is opened for a specific, measured in seconds or fractions of the time, called aging.
For high-quality images require a precise definition of exposure.
Established that the middle part of the curve, where the optical density is approximately equal to one, has the greatest potential for reproduction of the smallest or least-contrast detail. But it is above or below the limits of the straight part of the characteristic curve of reproduction parts photosensitive layer deteriorates. When shooting on a call or color film is especially important to find the right exposure. Under ideal conditions, when the mode display is strictly regulated, the degree of blackening density is directly proportional to light sensitivity and negative material exposure, which is a product of the photosensitive layer of illumination when shooting at shutter.
Optical density under the same conditions is directly proportional to logarithm of exposure.
Get the necessary exposure is possible in three ways. The first is to change the illumination of the subject. This can be achieved, taking off only in the interior under artificial lighting and increasing the power of the number of lights. When shooting on location in natural light this effect quite impossible. The second way is to set a different aperture numbers, the third - the various extracts.