DxOMark's measured ISOs vs. manufacturer ISOs

Started Mar 13, 2013 | Discussions thread
Martin.au
Martin.au Forum Pro • Posts: 13,273
Re: DxOMark's measured ISOs vs. manufacturer ISOs
1

cptobvious wrote:

It's hilarious how much deflecting in going on this thread. People can argue until they are blue in the face how Olympus (or Fuji) has a right to calculate their ISOs as they do because the ISO standard permits it. That is really not the point of the thread. The point of this thread as I started it was to point out that their measurements are outside the norm, and conveniently these measurements give a false impression of the E-M5's equal noise performance to Exmor APS-C/APS sensors when all exposure variables are not controlled.

In February 2011, DxOMark wrote their article explaining why measured ISOs are lower than manufacturer ISOs, because manufacturers base their ISO measurements on JPEG output and DxOMark bases their ISO measurements on RAW files: http://www.dxomark.com/index.php/Publications/DxOMark-Insights/Pushed-ISO-Let-s-make-it-clear/RAW-ISO-measures-are-inferior-to-manufacturer-ISOs-is-this-a-problem

However, this article was written before the X100 and E-M5 were tested. When this article was written, was there ever an camera released where the discrepancy between the two measurements was so significant? I have yet to find one. Maybe texinwien can tell us.

Same question for you capobvious.

I have two cameras here. One with DXO ISO of 211 for a camera ISO of 200, and the other with a DXO ISO of 107, for a camera ISO of 200.

What should I expect from each camera and how should I compare them?

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