DXOMark has completed the review of the flagship Canon EOS-1D X Mark III sensor. As you can see from the DXOMark score (of 83), which is little more than an indicator of sensor sensitivity, the new flagship of the range hasn’t performed quite as well as expected. The Mark III sensor is about 0.3 EV behind the EOS R and EOS 5D Mark IV in overall sensitivity, according to DXOMark.
From the data it clearly has some read-noise issues that have either not been addressed (at the sensor design level) or more likely is the result of a trade off with some other performance related criteria but what that could be is unclear.
One take-away from this is the ISO 50 setting is not a true ISO, in that it’s not half the exposure of ISO 100 (though that’s rarely the case anyway), and thus has lower noise. Indeed, the ISO 50 value is no different when measured to ISO 100, so there’s no advantage to the user in selecting it (though the camera may report a halving in exposure). With the same noise response as ISO 100, which is high at ISO 136 anyway, the Mark III is at clear disadvantage to Sony a9 II when using ISO 50 (or ISO100) for photographing high dynamic range scenes.
While that higher than expected read noise immediately lowers the overall sensor sensitivity (DXOMark score), the Mark III has a noticeably wider dynamic range than the Nikon D5 at low ISOs, but performs similarly at high ISOs. It’s also unlikely that the Nikon D6 sensor will be much different from the either the Nikon D5 or the Mark III at higher ISOs.
All images and data via DXOMark. The sensor review can be read at the DXOMark site.
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