Originally posted by Shanti why is the sports/ISO on DXOmark on the K3II lower than the K3 ,as the same sensor??
An interesting observation.
The difference is within measurement errors (and the overall score the same). Nevertheless, analyzing the measurements at DxO carefully is a good way to learn about said measurement errors.
The reported SNR values of K3 and K3-II are the same. However, DxO measures a slightly lower true ISO value for the K3-II, compared to the K3. This then translates over to a slightly worse Sports score.
However, I don't think the calibrated ISO sensitivities reported by DxO reflect the truth. It rather shows the limitation of DxO measured ISO calibration. It is a tricky measurement to start with, based on a tedious evaluation of clipping luminosity per color channel. Either this, or sample variation in quantum efficiency is this high.
E.g., at ISO400, calibrated ISO is reported as 359 vs. 380. A difference of 5%. I suggest this is the precision DxO is capable of achieving. The sports score can deviate by as much too. However, in practive the difference in the sports score will be smaller because it is affected by a dynamic range threshold which is less dependend on iso calibration.
Nevertheless, I take home the insight that ISO calibration is DxO weak spot wrt accuracy and accuracies better than 5% shouldn't be expected.
Last edited by falconeye; 09-08-2015 at 01:37 AM.