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Author Topic: Nikon results surprising  (Read 790 times)
sgegreen
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« on: July 16, 2013, 11:18:05 AM »

This a comment for this page on the website
I'm just wondering how the Nikon 1.8 lens can have lower scores than the Sigma 1.4 lens for every lens metric except distortion and yet end up with a higher overall score, 22 versus 21.

This is quite surprising.

Any ideas?
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John1
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« Reply #1 on: July 16, 2013, 06:34:04 PM »

Good point, I am wondering the same thing.
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Emilie_DxOMark
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« Reply #2 on: July 22, 2013, 04:31:22 PM »

Hello!

Thanks for your interest in DxOMark.

The DxOMark score is not computed with the optical scores. It takes more information into account (noise, dynamic range and color sensitivity of the sensor).

Best regards,

The DxOMark team
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noirdesir
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« Reply #3 on: July 23, 2013, 07:06:57 PM »

DxOMark score does not depend on the optical scores.
It depends on the measurement perfomed for Sharpness, Distorsion, TStop, and shading. Noise, dynamic range and Color depth are taken into account too.
But in this case both lenses were tested on the same camera (ie, noise and dynamic range are the same). Differences could come from the fact that the separate scores (DxOMark Score, sharpness, transmission, etc.) are not calculated at the same f-stop for a given lens. For example, if the vignetting score is based on the maximum vignetting (ie, wide open) whereas the DxO Score is valid for the best f-stop of a lens.

But looking at the data in detail that doesn't seem to be the case here, the Sigma is better at basically all f-stops. What might be the case here is differences in how things are averaged over the whole frame for the individual scores and the DxOMarks Score. The Sigma drops resolution earlier and deeper when going towards the corners.
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Emilie_DxOMark
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« Reply #4 on: July 24, 2013, 01:49:53 PM »

Hello!

You are right, here the difference is explained by the way resolution is weighted in the field:
For Sharpness score we weight acutance in the field while we do not for DxOMark score.

Best regards,

The DxOMark team
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