Use a slow ISO setting in sunny, daylight conditions.
If your digital pictures appear too dark or too bright, adjust the camera's ISO to remedy poor exposure. This feature -- known as the International Standards Organization, or American Standards Association (ASA) setting -- directly affects the amount of light used to expose pictures. Digital camera users can manually adjust the ISO, or light sensitivity, of their camera's image capturing sensor.
Understanding ISO Numbers
Typical ISO settings on a digital camera will range from 50 to 6400, or higher. The lower the ISO number, the more light the camera requires to properly expose a picture. Sunny, daytime photography turns out well at ISO 100 or 200. If you go inside a building, boost the ISO setting to 400 to account for the decrease in natural light. If you go into a room without windows and dim overhead lighting, choose an ISO of 800 or 1600. As available light decreases, increase the sensitivity of your digital camera sensor by boosting the ISO number.
When to Adjust ISO
Adjust ISO settings when light levels fluctuate or your subject increases its movement. Photographers use low ISO numbers, such as 50, when photographing still life scenes, portraits or brightly lit situations without movement. Typical ISO settings for indoor athletics range from ISO 400 to 800. Photographing high-school football players at night on a dimly lit field might require an ISO setting of 6400 to get a good exposure that not only freezes a player's movements, but also has enough light to see the player's face and uniform clearly.
ISO and Image Quality
As an ISO setting increases in number, image quality reduces. The individual pixels composing the image begin to look fuzzy, especially in the shadow areas of a picture. This lack of clarity is called digital noise.
Using the lowest ISO number possible at all times and adjusting your exposure by using the camera's aperture and shutter speed settings will give you better image quality.
Other Exposure Adjustments
Since aperture, shutter speed and ISO work together to create the exposure of a picture, learn adjust all three of these camera features.
Choosing the camera's aperture priority mode allows you to adjust both the ISO and aperture, while the camera chooses the shutter speed to balance the exposure. Choose a small aperture number to allow more light into the camera, so you can use a lower ISO number for optimal image quality.
Use the shutter priority mode of the camera to choose the shutter speed and ISO. The camera will then choose the aperture to balance the exposure. The slower the shutter speed, the more light reaches the camera's sensor during the exposure. However, don't set the shutter speed too slow or you won't capture a sharp picture of a moving subject. Choosing a shutter speed below 1/60th of a second will increase your chances for motion blur.
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