Just perception or real re quality, Canon vs Nikon

Started Sep 26, 2012 | Discussions thread
DigVis
Forum MemberPosts: 97
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Re: There is a real difference
In reply to rhlpetrus, Sep 28, 2012

rhlpetrus wrote:

DigVis wrote:

Under a daylight illuminant (CIE-D50), the D600 has a sensitivity metamerism index of 77, and the 5Dm3 74. In tungsten light (CIE-A) the D600 sensitivity metamerism index drops to 74, while the 5Dm3 scores 75.

And, possiblyt, these small differences in metamerism would not be of any practical relevance.

Agreed.

DxO istself discards them as performance indicators. The variablility seems quite large, they measure very different values from otherwise similar cameras/sensors, like D700 and D3, D300 and D300s. Their other measurements, like DR, Color depth and SNR curves, usually are very close for these pairs of cameras.

That is an interesting observation. The D300s for example, shows better SNR values than the D300, while having a worse metamerism index. That result would be consistent with a tweaked CFA (wider transmittance spectra). It could also be due to sample variation or measurement errors of course. My guess is that there are several reasons DxO doesn't stress the metamerism index results:

  • Possibly an uncertainty in how representative the values are (measurement errors / sample variation)

  • The importance for the general photographer. Most people seem to care more about visually pleasing than accurate colors (not least obvious in the "skin color" debate). One should probably never touch a saturation or vibrance slider if color accuracy were important.

  • Even with possible measurement uncertainties in mind, the trend seems clear: Modern DSLR sensors have worse color accuracy than the previous generation(s). For example, at daylight (D50), the 5D-> mk2-> mk3 metamerism indices have declined 84-> 79-> 74 respectively. In quantitative terms, 74 is more than 60 % worse than 84. Including the matamerism values in the DXO scores would probably make the results even more controversial and less generally accepted.

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