Editing Film speed (section)

===Current system: ISO{{anchor|ISO|ISO 6|ISO 2240|ISO 5800|Current ISO system}}===
<!-- This section is linked from inside or outside this article, preferable by "#ISO". Do not rename without keeping in sync. -->
The [[#ASA|ASA]] and [[#DIN|DIN]] film speed standards have been combined into the ISO standards since 1974.

The current [[International standard|International Standard]] for measuring the speed of [[color print film|color negative film]] is ISO&nbsp;5800:2001<ref name="iso.org"/> (first published in 1979, revised in November 1987) from the [[International Organization for Standardization]] (ISO). Related standards ISO&nbsp;6:1993<ref name="ISO_6"/> (first published in 1974) and ISO&nbsp;2240:2003<ref name="http"/> (first published in July 1982, revised in September 1994 and corrected in October 2003) define scales for speeds of black-and-white negative film and color reversal film, respectively.

The determination of ISO speeds [[#ISO 12232|with digital still-cameras]] is described in ISO&nbsp;12232:2019 (first published in August 1998, revised in April 2006, corrected in October 2006 and again revised in February 2019).<ref name="ISO 12232_2019"/><ref name="Gasiorowski-Denis_2019_ISO12232"/>

The ISO system defines both an [[arithmetic]] and a [[logarithmic scale]].<ref name="manual"/> The arithmetic ISO scale corresponds to the arithmetic ASA system, where a doubling of film sensitivity is represented by a doubling of the numerical film speed value. In the logarithmic ISO scale, which corresponds to the DIN scale, adding 3° to the numerical value constitutes a doubling of sensitivity. For example, a film rated ISO&nbsp;200/24° is twice as sensitive as one rated ISO&nbsp;100/21°.<ref name="manual"/>

Commonly, the logarithmic speed is omitted; for example, "ISO&nbsp;100" denotes "ISO&nbsp;100/21°",<ref name="Graves_1996_Zone-system"/> while logarithmic ISO speeds are written as "ISO&nbsp;21°" as per the standard.

{{Sequence
| prev = [[ISO 5]]
| list = Lists of ISOs
| curr = ISO 6
| next = [[ISO 7]]
}}