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Exposure is usually controlled by changing the lens aperture (the amount of light it gathers), the shutter speed (how long light is gathered) or sensitivity (how strongly the film or sensor responds to light). Changing exposure does not change the exposure range. [3] Three exposures of the same image at different exposure levels.
On a number of cameras this is the default or standard setting. The camera measures the light intensity in several points in the scene and then combines the results to find the setting for the best exposure. The method of calculation can be different from camera to camera. The actual number of zones used varies widely, from several to over a ...
The use of radiometric units is appropriate to characterize such sensitivity to invisible light. In sensitometric data, such as characteristic curves, the log exposure [4] is conventionally expressed as log 10 (H). Photographers more familiar with base-2 logarithmic scales (such as exposure values) can convert using log 2 (H) ≈ 3.32 log 10 (H).
The f-number (relative aperture) determines the depth of field, and the shutter speed (exposure time) determines the amount of motion blur, as illustrated by the two images at the right (and at long exposure times, as a second-order effect, the light-sensitive medium may exhibit reciprocity failure, which is a change of light sensitivity ...
The picture on the right shows the device of the Zenit - E model, mounted on a left side of the camera. The inner (flat) circle rotates with the help of the knob and sets the film sensitivity (visible in both DIN and ASA units through tiny windows). The outer circle is coupled to the moving O - shaped marker in the scale on the left and must be ...
Each number represented an increase of 1/3 in speed, typical plate speeds were between 10° and 25° Warnerke at the time. His system saw some success but proved to be unreliable [3] due to its spectral sensitivity to light, the fading intensity of the light emitted by the phosphorescent tablet after its excitation as well as high built ...
Once the camera is sensitive to the full-spectrum, external filters can be used to selectively filter portions of the UV, visible and infrared to achieve various effects. For example, a standard red #25a can be used to include red light and infrared light together, yielding particularly strong two-toned color images of a reddish nature except ...
Once the sensitivity to light of the recording surface (either film or sensor) is set in numbers expressed in "ISOs" (e.g. 200 ISO, 400 ISO), the light emitted by the scene photographed can be controlled through aperture and shutter-speed to match the film or sensor sensitivity to light. This will achieve a good exposure when all the details of ...