I just bought a second hand Sigma lens (50mm Art f/1.4) for my Canon 7D2 body (Mark II). This combination yields a very serious back-focus problem:
- With no micro-ajustements correction on my body, the plane in focus is about half an inch further than the one I am targeting using the viewfinder: for a portrait of someone a few meters away, when focusing on the eye, the focused area is somewhere between the eye and the ear.
- With the maximum micro-ajustements correction in my body (-20 from the -20/+20 range), the back-focusing problem is attenuated, but still there. I am guessing -25 or -30 could have solved this but it is not available.
- when using Liveview to focus, everything is OK.
I was using f/1.4 when trying to calibrate micro-adjustments.
Do you thing using the Sigma USB dock to tune the lens focusing parameter would solve this? Should I sell it back and buy another copy?
Two things happened this weekend;
- A friend tried my copy and it worked perfectly after a few adjustment on his 5DIII.
- I managed to get an other copy of the Sigma lens from my photography club... and it worked also fine on my 7D2 body after some tuning.
So I am going to sell my copy and get a new one... fingers crossed ! (and I will never know if the dock would have solved this issue...)