What is ISO, and how does it affect my photos?
Asked 7/15/2010
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What does the ISO setting on a camera represent, and how does changing it affect exposure and image quality? What should a photographer watch out for when choosing a low or high ISO?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
16y ago
2 Answers
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Changing the ISO setting in digital camera's is like changing the gain (amplification) of your photo sensors. With a low ISO setting (e.g. 100) you don't amplify the signal from the sensors. But using a high ISO setting (e.g. 1600) results in an amplification of the signals registered by the sensors. A high ISO setting usually results in more noise in your images so try to keep the ISO as low as possible.
This article explains various sources of image noise: http://en.wikipedia.org/wiki/Image_noise
Originally by user19. Source · Licensed CC BY-SA 4.0
user19
16y ago
0
Generated from our catalog & community — verify before relying on it.
ISO is a standardized measure of sensitivity. In film, it describes how sensitive the film is to light; in digital cameras, it’s similar to increasing the sensor signal (gain/amplification).
Lower ISO settings, such as 100, use less amplification and usually give cleaner images. Higher ISO settings, such as 1600 and above, make it easier to shoot in lower light or use faster shutter speeds, but they typically introduce more visible noise. In film this appeared as grain; in digital images it appears as noise.
ISO is part of exposure: the camera uses ISO along with shutter speed, aperture, and sometimes flash to reach the desired brightness.
In practice, use the lowest ISO that still lets you get the shutter speed and aperture you need. Raise ISO when there isn’t enough light or when you need to avoid blur from camera shake or subject movement. The main trade-off to watch for is increased noise at higher ISO settings.
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