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Olympus E-PM2 Actual ISO vs IS0 set in camera?

Started Aug 17, 2014 | Discussions thread
BJL Veteran Member • Posts: 9,343
Misinterpretation by DXO of the definition of ISO speed

What DXO insists on referring to as "ISO" is what the actual ISO standard 12232 describes as the lower limit of the exposure latitude of the camera at a given "ISO speed" setting: basically a measure of how much exposure you can give the camera at that setting without saturating the sensor and blowing the highlights: "SSAT" in the jargon of that ISO standard.

ISO standard 12232 actually recommends a different measure of sense speed or sensitivity, "SSNR40", which is basically about getting a SNR of at least 40:1 in the mid-tones; this measured shadow handling, and is much closer to what the ISO film speed refers to.

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