Some photographers use external light meters (outside the camera) to determine exposure. Correct exposure is the combination of aperture and shutter speed for a given ISO that retains as much detail as possible in both the dark and light areas of an image. A lux meter is an external light meter that was not designed for photography and so does not compute aperture and shutter speed for a given ISO. The photographer must make the calculation herself. EV———-Lux 0————2.5 1————5 2————10 3————20 4————40 5————80 6————160 7————325 8————650 9————1,300 10———–2,600 11———–5,100 12———–10,000 13———–20,000 14———–40,000 15———–80,000 16———–160,000 17———–330,000 Writer Bio
