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RF 28-70mm soft left edge or normal performance?

Started Feb 28, 2021 | Discussions thread
OP mvert Forum Member • Posts: 64
Re: RF 28-70mm soft left edge or normal performance?

Dan W wrote:

Did also some close distance testing inside. Left is also here pretty bad compared to right side. Siemens stars are crops from the extreme corners. Focused camera center of the lens and took picture (ibis off) and set lens to manual focus. Moved camera on tripod head (without moving tripod) so that I could set Siemens star in the each corner and took picture and combined all in this image.

Test setup 5 images from tripod, focus center.

Some more picture can be seen on: https://mve.kuvat.fi/kuvat/Testikuvia/

Site might be slow outside Finland.

OK, maybe I'm confused but each of these clearly shows the target taken at an angle??? DOF plays a definite roll in IQ

You are right, the corners are taken at an angle. I tried to explain test procedure in the text before image.

"Did also some close distance testing inside. Left is also here pretty bad compared to right side. Siemens stars are crops from the extreme corners. Focused camera center of the lens and took picture (ibis off) and set lens to manual focus. Moved camera on tripod head (without moving tripod) so that I could set Siemens star in the each corner and took picture and combined all in this image."

This Siemens star was just next to that test target in the center. I didn't have big enough space to make test setup where I could just take one picture from 5m and have center and all corners at the same plane of focus. Recomposing made that test possible and it showed me, that left side of the image was really much worse than right side.

I send that lens back to dealer and got a new one after few months. Second copy of the lens was much better. Extreme corners and edges aren't perfect on the second copy either when shot at f/2, but they get better on smaller aperture. This didn't happen on the first copy of the lens and left edge of the whole image was soft even on f/11.

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