ISO
This abbreviation refers to the International Organization for Standardization. In the field of photography, it is a method for determining how sensitive digital imaging systems and photographic films are, as well as measuring and specifying that sensitivity. The larger the ISO number, the more sensitive the camera is to the presence of light. Because cameras include a range of ISO settings, users are able to select the ISO value that is most appropriate for the subject matter or environment being captured on film.
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