By chance today I met a young girl with the new 650D and 18-135 lens and happened to have my lens in my bag. We set both cameras to AV and autofocus and took the same photograph and the LCDs on both were slow to get the green square so I got my answer. Just not fast enough for street photography as everyone says so no surprise there but I thought as I started this thread I should reply. I am still happy with my 600D in general but pleased I bought the sony 5n especially as it is so hot and humid and it is so light. have a nice weekend everyone.