I have been using my 70D with Tamron 28-75 f/2.8 and could see that there is a slight issue with foucssing at f/2.8. The subject doesn't seem to be sharp compared to Canon 40mm f/2.8 STM lens. I read on the internet that many people have the same problem while using the center focus point in Canon 70D with non STM lenses at wide apertures.
Does everyone have this problem? How is everyone overcoming it? Using Live View? Using a different focus point than the center? Using Zone focussing?... etc. What would be the best way to overcome this issue as I see that Canon is not acknowledging it as a problem.
I have done some tests at 40mm f/2.8 by using a focus point just above the center and also with the center zone, but can't tell if there is any improvement compared to the Canon 40mm STM lens.