Forum Twitter Facebook Google + RSS

Author Topic: Bias against macro lenses?  (Read 1986 times)

Offline rouckas

  • Newbie
  • *
  • Posts: 2
Bias against macro lenses?
« on: April 07, 2013, 01:19:02 pm »
This a comment for this page on the website
I think that your score rating is biased against lenses with high apertures (typically macro lenses) The sigma 105 mm is better or equal to Samyang 85 mm at equivalent apertures (according to your review), yet the Samyang has much higher score. It seems that this is because Sigma allows high apertures to f/36 (being a macro lens), which are heavily affected by diffraction. Averaging these high apertures into the overall score leads to lower rating? Samyang is better, because it goes to f/22 only!?

BTW, I think that I already submitted this comment earlier...

Offline Emilie_DxOMark

  • Administrator
  • Hero Member
  • *****
  • Posts: 530
Re: Bias against macro lenses?
« Reply #1 on: April 10, 2013, 11:38:11 am »

Thanks for your interest in DxOMark.

We rank lenses with two main scoring systems: DxOMark score and Sharpness score. For both, we compute each score for each couple focal/aperture, take the best for each score and average each focal results (see our documentation

As the use case for DxOMark is more challenging the lens with wider aperture mounted on camera with a good performance in lowlight will score higher.
For sharpness, we only take the best aperture for each focal.
So the high apertures are mostly not taken into account for the two scores as these apertures do not provide the best score (neither DxOmark score nor Sharpness score) because of the diffraction impact.
In the case you report, the Samyang achieves a higher DxOMark score (because of its wider aperture) but gets the same sharpness score (their best sharpness is very close).
I hope you will find these few lines useful.

Best regards,

The DxOMark team