So... I finally come to a decision to go with the OM-D... Is there any big hand users out there?

Started Mar 13, 2013 | Questions thread
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texinwien Senior Member • Posts: 3,320
Some Clarifications

It's a bit of a complex topic, and I made some injudicious statements and/or outright misstatements (but never out of malice). Corrections below, inline:

texinwien wrote:

scott_mcleod wrote:

Some of what you are seeing in the superiority of the Oly is an artifact of the E-M5 under-rating its ISO by about a full stop across the range (i.e. ISO 1600 on the camera is actually only 782)

Hi Scott, that's an oft-repeated mantra, but it is a misconception - one that DPReview have been very specific in countering - I will include some links to official DPReview statements at the end of this post.

The ISO 12232:2006 standard (Exposure Index Standard) only applies specifies two new methods (SOS and REI) that camera manufacturers may use to determine EI to the three that were already contained in the original version of the standard. These two standards are the ones most often used by camera manufacturers today (and the appropriate one of these two must be mentioned in a RAW file's EXIF). These two methods apply only to the sRGB output of a camera (practically, the out of camera JPEGs). It says They (the two new methods) say nothing about the RAW files, and the 'under-rating' you mention here is only seen in the RAW files. As such, that 'under-rating' is allowed by the ISO standard. Meaning, in effect, that it's not an under-rating at all.

The E-M5 is standards-compliant in regards to ISO 12232:2006.

While the DxO 'Measured ISO' numbers are very helpful for photographers and consumers who take the time to understand what they mean, they have nothing to do with actual ISO Exposure Indices / EIs / ISO Settings, as defined by the one and only standard that counts. DPReview has also been specific in stating that it's improper to mix the DxO numbers up with  actual ISO Exposure Indices / EIs / ISO Settings.

It gets worse as you go higher. This is why it looks so clean compared to the competition at any "equivalent" ISO. The GH2 also under-rates but not nearly as much. The lowly G5 is very close to spec.

This is also a commonly-held misconception, but it is also incorrect (and has also been directly addressed and contradicted by DPReview employees).

I suggest that you read the following statements from Andy Westlake (Technical Writer at DPReview), who took the time to explain some details about DPReview's testing regime and ISO, with the E-M5 tests and measurements as the original grounds for the discussions that were started.

This DPReview article on ISO may also help to clear up any lingering misconceptions you might still have.


To the OP: Scott's explanation for the E-M5's apparent superiority is technically incorrect, which fact is backed up by official statements from DPReview employees. The superiority you are seeing is actual*, and cannot be explained away by any supposed 'tricks' performed by Olympus (Olympus has performed no tricks w/r/t ISO, as a matter of fact, according to the ISO standard), although many try to do exactly that, anyway.

* Actual except for any differences that would be suggested by differences between DPReview tested ISO Sensitivity for the compared cameras (which differences are MUCH LESS than those reported by DxOMarks tests, to the point of being, most likely, undetectable by the human eye)


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Panasonic Lumix DMC-GM5 Olympus E-M5 II Olympus 12-40mm F2.8 OnePlus One Canon EOS 300D +20 more
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