If you are an amateur or professional photographer fortunate enough to catch a blood-orange sun sinking behind the mountains, the wrong International Organization for Standardization setting can ruin your photo. That's because the ISO setting -- which is standard on nearly every digital camera -- controls the camera's sensitivity to light. The proper ISO settings for outdoor photography is dependent on the time of day that a picture is taken.
In photographic terms, ISO is a numerical expression of a camera's image sensor sensitivity. This sensitivity is affected by light conditions. A camera on a high ISO setting is very sensitive to light and is optimal for low-lit conditions. A camera on a low ISO setting is less sensitive to light, which is advantageous in situations in which there is ample light. Before the development of digital cameras, photographers could only change the ISO setting by manipulating the film itself.
Digital cameras typically come with ISO settings that include 50, which is the lowest setting; 200; 400; 800; 1600; and 3200. Low-range ISO settings, such as 100 and 200, typically indicate excellent light conditions. Midrange settings, such as 400 and 800, will account for less natural or artificial light. High-range settings, such as 1600 and 3200, will adjust for poor lighting conditions.
Outdoor photography can occur in various light conditions. For landscape pictures in optimal light conditions, use the camera's base ISO setting -- 50, 100 or 200 -- for the best quality photo. If the sky is overcast, increase the ISO setting to 400 or 800 to adjust for the lower-light conditions. Outdoor pictures taken at night may require midrange ISO settings such as 800 or 1600; but if you use a tripod to steady the shot and prevent blurring, you can set the ISO to 200 or 400 and increase the shutter speed for better results. Using flash at night in outdoor photography is problematic if your subject is more than 15 or 20 feet from the camera. It's better to set the camera to a low or medium ISO setting and use a tripod for the best quality photos.
Advantages and Disadvantages
Low ISO settings tend to produce higher quality outdoor images, even at night. However, if you haven't set the right shutter speed or aperture -- the diameter of the lens iris that controls how much light gets into a shot -- then a picture taken on a low ISO setting can turn out blurry or indistinct. Medium ISO settings in outdoor photography can help you take a clear picture in overcast and lower-lit conditions, but high ISO settings may also degrade the quality of your photos. This is known as "noise" in photographic terms, and refers to dark spots, irregular colors and an overall grainy appearance of a photo.
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