Third-stops are especially important as theyвЂ™re the increment that most cameras use for their settings. Photographers also talk about half-stops or third-stops. As you can probably see, for shutter speed the rule is really simple: to increase your exposure by a stop, halve your shutter speed to decrease your exposure by a stop, double it. Changing your shutter speed to 1/200th of a second (halving the amount of light let into the camera) reduces your exposure by a stop. So for example, if you have the shutter speed on your camera set to 1/100th of a second, increasing your exposure by one stop would change the shutter speed to 1/50th of a second (letting twice as much light into the camera). One stop is equal to a halving (or a doubling) of the amount of light let into the camera by that factor. Instead, stops are used to describe relative changes in aperture and exposure time. Since exposure is valueless-you donвЂ™t look at a scene and describe it as a 12 stop photo for example-there is no way to talk about things in absolutes. If the aperture is too wide or the exposure time too long, then all youвЂ™ll get is a white photo conversely, if either of them is too low, youвЂ™ll just get a black photo. Although exposure is basically quantity-less, thereВ are a range of combinations of aperture and exposure time that will create a good photographic exposure. When you take a photograph, the exposure is determined by the area of the aperture and the exposure time (also called shutter speed). RELATED: Your Camera's Most Important Settings: Shutter Speed, Aperture, and ISO Explained

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