DxOMark's measured ISOs vs. manufacturer ISOs

Started Mar 13, 2013 | Discussions thread
Martin.au Forum Pro • Posts: 13,276
Re: DxOMark's measured ISOs vs. manufacturer ISOs

Jack Hogan wrote:

Mjankor wrote:

Nobody's stopping you from doing that, in fact you can check DPR's 'comparometer' as per my previous post. Too bad that if one manufacturer calls ISO 400 what another calls ISO 1600 you'd be unknowingly coming to the completely wrong conclusion... alas, for some ignorance is bliss


I'd like you to explain this.

Perhaps an example would help. Suppose one wanted to compare the noise performance of two different cameras in the kind of conditions that required ISO 200 in order to satisfy his artistic constraints for blown highlights, DOF and blur - and came across this comparison on a fictitious but nevertheless well respected site:

What erroneous conclusion would he reach?

PS Did I mention that the current standard basically allows manufacturers to label in-camera ISOs as they please? 400, 200, 100 or whatever they like? That's the EM5 at 25k, by the way, but I, the manufacturer, decided that today it felt more like 200 Clearer now?

Oh, right, so in your example, we can throw exposure out the window.

Now you're proposing testing 1 camera with 1/100 exposure time, against one with 1/4000 exposure time. Why?

In short, no, it's not clearer.

The OM-D meters like other cameras, and has a final image brightness like other cameras. It can use the same exposure as other cameras for a given final image brightness. Not sure what you think is going on, but it doesn't appear to align with real world tests.

The OM-D's manufacturers ISO rating is pretty well in line with most other cameras. Maybe you can present us with an example of a camera where the manufacturer has declared their ISO values off by a significant amount.

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