I recently made a big upgrade (body and several lenses) into the world of DSLR and I would be incredibly happy except for the fact that I can't use wide apertures due to repeatable problems with acquiring focus. I started out with a Canon T3i, but I noticed that in many pictures the main subject (directly under the center AF point which was manually selected - verified in DPP) was slightly out of focus. Not completely blurry, but enough to spoil the shot. I also noticed that objects well outside of the AF point, which were slightly closer or slightly farther, were in amazingly crisp focus. At the time, I didn't know the terms "front focus" or "back focus".
Thinking that the 60D would have better focus due to its improved focus sensors, I changed from the T3i to the 60D. I still found myself with the same problem. Especially when taking portraits and candids, the subject's face was always a bit fuzzy while another part of the frame was in sharp focus. Eventually I realized two things: first, the part of the frame that was in focus varied based on the lens I was using. Second, the problem was worse at wide apertures due to the shallow depth of field. Obviously that second one goes without saying, but I point it out to show that I understand how DOF varies with aperture size.
As I started to read about this problem, I learned the terms "front focus" and "back focus". At that point I was able to say that the Canon 50mm 1.8 II lens was front focusing, the Sigma 30mm 1.4 lens was front focusing (but not as much as the 50mm), and the Tokina 16-50mm 2.8 lens was back focusing. The two kit lenses (Canon 18-55 and 55-250) were pretty close in terms of focus. The 18-55 was front focusing a tiny bit and the 55-250 was basically spot on. Of course the 18-55 and 55-250 have smaller maximum apertures, so that probably makes any focus error less apparent.
All of these focus issues are noticeable in real-life situations and are extremely apparent in contrived scenarios such as setting up batteries or other identical contrasty objects. I don't think it's a problem with my technique, because I can set up a test with the body on a tripod, and I can reproduce the focus characteristics 100% of the time by changing lenses. If I put the 50mm 1.8 on, it will focus on the front object even though the AF point is on the middle object. If I replace it with the 16-50, it will focus on the back object even though the AF point is on the middle object. First time, second time, every time. And this wouldn't matter except for the fact that the same problem manifests itself in real-life shooting.
After investing about $2,500 in camera gear, I can't get sharp photos at wide apertures because the lenses won't focus where they are supposed to. Of course I can stop them down to f/8 and make the problem disappear. But if I wanted to shoot at that exposure, I would just go back to my P&S.
So my question is this: are wide apertures useless without the ability to microadjust? In other words, do I need at least a 7D if I want to actually get photos that are focused on the object at the AF point? I don't think it's a body defect since I saw the same problem with the T3i and the 60D. And I don't think it's a problem with my technique, since I can predict the exact focus error of any shot almost 100% of the time. What should I do here? And a bigger question is, why would Canon even sell a body that doesn't allow these glaring problems to be corrected?