iso....... when we had film it was the speed, a number that defined how long the film (now ccd) took to be fully exposed by a measured amount of light. light is adjustable with shutter speed, twice as long, twice as much light, and aperture, twice as big, etc (most of the numbers are twice). So you can drop the shutter down increase the aperture and the same amount of light will reach the film/ccd.
Say,,,, if the iso is 100, then 200iso will accept it twice as quick, up the iso and pick a faster shutter speed, same amount of exposure. Handy for fast buggys……. The trade off is grainy pictures or less colour possibly.
3 things to play with, shutter speed, aperture and iso
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