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An example of the use of f-numbers in photography is the sunny 16 rule: an approximately correct exposure will be obtained on a sunny day by using an aperture of f /16 and the shutter speed closest to the reciprocal of the ISO speed of the film; for example, using ISO 200 film, an aperture of f /16 and a shutter speed of 1 ⁄ 200 second. The f ...
Illuminance is measured using a flat sensor; if the common value of C = 250 (unit: lux s ISO=lm s/m 2 ISO) is used, an EV of zero (e.g., an aperture of f /1 and a shutter time of 1 sec) for ISO = 100 corresponds to an illuminance of 2.5 lux (0.23 fc). At EV = 15 (the "sunny sixteen" amount of light) the illuminance is 82,000 lux (7600 fc). For ...
On a sunny day at ISO 100 ("100 speed film"), the aperture is set to f /16 and the shutter speed (i.e. exposure time) to 1 / 100 or 1 / 125 [2] seconds (on some cameras 1 / 125 second is the closest available setting to 1 / 100 second). On a sunny day at ISO 200 and aperture at f /16, set shutter speed to 1 / ...
For example, the photographer may prefer to make his sunny-16 shot at an aperture of f /5.6 (to obtain a shallow depth of field). As f /5.6 is 3 stops "faster" than f /16, with each stop meaning double the amount of light, a new shutter speed of (1/125)/(2·2·2) = 1/1000 s is needed. Once the photographer has determined the exposure, aperture ...
The ISO arithmetic speed has a useful property for photographers without the equipment for taking a metered light reading. Correct exposure will usually be achieved for a frontlighted scene in bright sun if the aperture of the lens is set to f/16 and the shutter speed is the reciprocal of the ISO film speed (e.g. 1/100 second for 100 ISO film).
For example, f /8 lets four times more light into the camera as f /16 does. A shutter speed of 1 ⁄ 50 s with an f /4 aperture gives the same exposure value as a 1 ⁄ 100 s shutter speed with an f /2.8 aperture, and also the same exposure value as a 1 ⁄ 200 s shutter speed with an f /2 aperture, or 1 ⁄ 25 s at f /5.6. [citation needed]
Cameras with focal-plane shutters—even if they had PC connectors with X, F, M, or S-sync delays ("xenon sync" with zero delay and flashbulbs with peak delays of 5, 20, and 30 ms)—could not be used at speeds that attenuated guide numbers with most types of flashbulbs because their light curves were characterized by rapid rise and fall rates; the second shutter curtain would begin wiping ...
Many digital cameras have a display setting and possibly a physical dial whereby the photographer can set the camera to either over or under expose the subject by up to three f-stops in 1/3 stop intervals. Each number on the scale (1,2,3) represents one f-stop, decreasing the exposure by one f-stop will halve the amount of light reaching the ...