Sony vs Sigma blue and gray resolution measurements

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docmaas
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Sony vs Sigma blue and gray resolution measurements
7 months ago

For methodology please read these posts first for background on what kind of testing I am doing: http://www.dpreview.com/forums/thread/3669097#forum-post-53665179 and http://www.dpreview.com/forums/post/53653391

Sony Sigma civil war the Blue and the Gray

Well, here's blue from the Koren chart provided by Erik.

conditions: aperture f5.6 sigma 18-35 f1.8 at 18mm.

Camera further away from the target than yesterday.

SPP used to develop Sigma with sharp -7. Sony IDC used to develop sony with all neutral settings. Iridium Developer used to develop both with all neutral settings.

Note while you might be able to assess relative mtf it still has nothing to do with any other mtf measurement.

First the blue:

Sony A7r response to the blue chart. f5.6 18mm sigma 18-35 f1,8 iso 100

Sigma SD1 response to the blue chart. f5.6 18mm sigma 18-35 f1,8 iso 100

The sony response to the blue is surprisingly fat. It makes me wonder if the IDC is boosting the blue. Let's take a look at the same chart via iridient developer:

Sony A7r response to the blue chart. f5.6 18mm sigma 18-35 f1,8 iso 100

Indeed, Iridient shows a much more neutral response. However note that Iridient seems to find more detail in the sony image than sony does. Interesting.

I wonder how iridient compares to spp for the blue:

Sigma SD1 blue response as developed by Iridium -- nearly identical to spp

Note that while spp sharp is set to -7 no sharpening at all on Iridium. Looks like -7 is very close to 0 sharpening in actuality.

Now the gray:

Sony a7r aps-c mode response to the gray chart. f5.6 18mm sigma 18-35 f1,8 iso 100

Sigma SD1 response to the gray chart. f5.6 18mm sigma 18-35 f1,8 iso 100

Now the crops of the charts:

Sony

Notes:

In both cases the Sigma outperforms the sony.

The sony response to both the blue and the gray is surprisingly much more plump from sony Image Data Converter than that from Iridient indicating that IDC may be boosting response during processing.

Sigma spp results match those from iridient almost perfectly. In particular the sharpness setting of -7 seems to match the no sharp setting on Iridient.

Mike

Sigma SD1 Sony Alpha 7R
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