Just wanted to share what I have been experiencing with my 70D... Since I purchased this body, I have been getting inconsistent focusing with f4 and narrower so I limit myself in using 5.6 and abve to get the sharpness I want.
Recently, I encountered an ERR 01 notice and after re starting my camera, everything is sharp but for a period of time only, may I say after 20 - 25 shots the problem gets back. Again i have been very curious about it. Last 2 days ago, I opened my front elements (24 -105) and noticed the six screws of the lens a bit loose, I tightened them up correctly after cleaning the glasses.
Made some shots and there was a big difference, it became consistent (up to this moment) in its sharpness.. I get 8 out of 10 rate in hand held shots compared to 2 out of 10 before. But I am not saying that I was able to fix the problem though, I will still observe for weeks or maybe months... I will post some shots if it did not revert to its previous state.
I want to hear your point of view about this, Does what I stated can really affect the camera's performance? Hope you'll have time in sharing your thoughts folks. Thank in advance.