ASA
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Abbreviation for American Standards Association (Now ANSI). In photography, Used in conjunction with a number, e.g., ASA 400, refers to film or sensor "speed" or sensitivity to light. The higher the number, the more sensitive the film/sensor, allowing for faster shutter speeds and/or smaller f/stops. The ASA scale has been replaced by the one from ISO (International Organization for Standardization), the scale numbers remain the same; e.g. ASA 100 = ISO 100 (See ISO for further explanation)
