GH3 studio shots available

Started Mar 11, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Shouldn't ISO125 be compared
1

SHood wrote:

According to DXOMark ISO125 on the GH3 is the equivalent of ISO200 on the E-M5 with RAW. We should probably be comparing these.

No. It doesn't follow from the DxO "measured ISOs" that the DPR studio scene samples are not comparable. The studio scene samples are comparable provided that the two cameras have received the same amount of light on the sensor at the same camera ISO setting. This can be verified by means of RawDigger together with the info we have on DxO "measured ISO".

The GH3 has a DxO "measured ISO" of 149 at a camera ISO of 200. The E-M5 has a "measured ISO" of 107 at a camera ISO of 200. If the two cameras have received the same amount of light on the sensor, the ratio between the "measured ISOs" should be the same as the ratio between the saturation levels of the RAWs. The saturation levels can be measured (by downloading the RAW files and checking them out via RawDigger) as the green channel average (since the green channel is the strongest) divided by the clipping point. The GH3 saturation level thus measured is 0.138 and that of the E-M5 0.097.

The ratio between the "measured ISOs" is 149/107 = 1.39 and the ratio between saturation levels 0.138/0.097 = 1.42 so if anything, the GH3 received a bit more light on the sensor than the E-M5 but the difference so small as to be of little practical importance.

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