Olympus OM-D (EM-5) comparison samples are now.. (continued)

Started Mar 17, 2012 | Discussions thread
Andrew Westlake Senior Member • Posts: 2,928
Sorry, Bob, but you've made a critical mistake

OK, I'm not going to reply to this in detail becuase you've made one assumption that's critically wrong:

bobn2 wrote:

We test ISO, essentially according to the SOS method, and present the results in every review.

You are testing meter calibration there. Different thing from sensor response.

This is incorrect. We're not tesing meter calibration - the camera's metering isn't involved in our ISO testing at all. Instead, we set the lighting up to a critically-controlled level (to within 1/10 EV) using a calibrated external lightmeter, then shoot the test camera in manual exposure and look at the JPEG output brightness of a specific grey target. We also double-check against a couple of recently-tested cameras to ensure consistency across reviews, and periodically check our calibrated photographic light meter (which reads in EV) against an independent scientific lightmeter (that measures in Lux, so is a bit tedious to use as a matter of course). We literally don't look at camera's meter at all during this process.

Just to pre-empt what would be the smart next question, all of our tests use the same lighting type as the ISO test, i.e. daylight-balanced fluorescent.

We don't actually do metering calibration tests as a matter of course, as cameras tend to behave themselves reasonably well in spot or partial modes, but maybe we should do them more often. However we did do one for the Sony NEX-5 as it meters so oddly hot, so you can see what it looks like here:

http://www.dpreview.com/reviews/SonyNex5Nex3/12

Seriously, you don't have a monopoly on understanding camera testing. And as far as I'm aware you've bever been into our studios, so you don't actually know what we do and what confounding factors can be in place while we're testing.

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Andy Westlake
dpreview.com

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