Sigma 70mm Macro problem focusing

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Batzorig
Batzorig Regular Member • Posts: 135
Sigma 70mm Macro problem focusing

I have a Sigma 70mm f2.8 EX DG Macro lens and thought it was a perfect lens for copy works. But I noticed it lost sharpness badly on the bottom left corner. Perhaps some people would say to revise my shooting technique. But I have been doing this long enough that I know it is a lens thing ( I use strobes, tripod, f8 aperture and do my best to align the camera well).

I don’t know if it was like that from the beginning or it was caused by an accident. On one occasion my camera (previous camera) fell to the ground while on tripod because one of the legs were not properly tightened. My Sigma lens' focus switch button fell off and got a slight crack which I fixed with Quick Steel glue. After sticking back the focus button in place it just worked as before so I didn’t bother much at the time. Now I wonder if the accident had caused shifting of internal elements, thus the left corner being sharply out of focus. I feel like this is not a normal thing as macro lenses supposed to be sharp from corner to corner. Your opinions and advices are greatly appreciated. This lens is my main work horse and wondering if it’s time to change lens.

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Bat

 Batzorig's gear list:Batzorig's gear list
Canon EOS 5D Mark II Canon EOS 5DS R Canon EF 50mm F1.8 II Canon EF 70-200mm F4L USM Sigma 70mm F2.8 EX DG Macro +3 more
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