Everything is always better in manual! However practice makes perfect. I never use auto focus due to the fact I've always slated my photographer mates for doing so. you will only notice if you zoom right into the image, however no matter your framing and lighting the 1st thing a sales person will do is zoom right in and go through ur images sharp, sharp, soft etc. Im ranting ur not doing billboards, as DK says a constantly focusing camera works make sure u set the right focus point. The downside is will focus on the most amount of detail around ur target, like if ur looking at a rally car trying to focus on the drivers eyes it will focus on the mud splats on the bumper. Just sit at the start of the runway at Heathrow airport and practice.