July 29, 2014, 10:23:20 AM

Author Topic: DxO Review of Sigma 50mm 1.4 DG HSM Art  (Read 361 times)

mackguyver

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DxO Review of Sigma 50mm 1.4 DG HSM Art
« on: April 17, 2014, 11:02:32 AM »
Review

It looks like the only real surprise is the TStop of 1.7.  Not a big deal, but a bit unexpected given the TStop of 1.5 for the Sigma 35A.

Comparison to the Canon 50L and 1.4
« Last Edit: April 17, 2014, 11:10:41 AM by mackguyver »
EOS 1D X, 5DIII, M + EF 24 f/1.4II, 50 f/1.2, 85 f/1.2II, 300 f/2.8 IS II || 16-35 f/4 IS, 24-70 f/2.8II, 70-200 f/2.8II || TS-E 17 f/4, 24 f/3.5II || M 22 f/2, 18-55 f/3.5-5.6 IS || 1.4x III, 2x III

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DxO Review of Sigma 50mm 1.4 DG HSM Art
« on: April 17, 2014, 11:02:32 AM »

Rudeofus

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Re: DxO Review of Sigma 50mm 1.4 DG HSM Art
« Reply #1 on: April 17, 2014, 11:20:29 AM »
Since all of these fast lenses have severe vignetting wide open, I wonder how they measure T stops. Do they measure average across the whole frame, or only in the center, or somewhere in between these two extremes?

mackguyver

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Re: DxO Review of Sigma 50mm 1.4 DG HSM Art
« Reply #2 on: April 17, 2014, 11:24:44 AM »
It looks like they measure it across the frame, and they don't mention vignette compensation:
http://www.dxomark.com/About/In-depth-measurements/DxOMark-testing-protocols/Light-transmission
EOS 1D X, 5DIII, M + EF 24 f/1.4II, 50 f/1.2, 85 f/1.2II, 300 f/2.8 IS II || 16-35 f/4 IS, 24-70 f/2.8II, 70-200 f/2.8II || TS-E 17 f/4, 24 f/3.5II || M 22 f/2, 18-55 f/3.5-5.6 IS || 1.4x III, 2x III

Rudeofus

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Re: DxO Review of Sigma 50mm 1.4 DG HSM Art
« Reply #3 on: April 18, 2014, 04:34:05 AM »
It looks like they measure it across the frame, and they don't mention vignette compensation:


That would explain why a slow IS zoom like the 24-70 F/4 IS has T=4 whereas all fast lenses have T stop significantly above their largest aperture. In other words, this T stop number is a poor substitute for their vignetting number and as such should be considered most useless.

Very confused ...

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Re: DxO Review of Sigma 50mm 1.4 DG HSM Art
« Reply #3 on: April 18, 2014, 04:34:05 AM »