I found with my camera that when using the zoom, depth of field becomes a real problem. At PI over the weekend I've got shots where part of the bike is in focus, but the DoF is so shallow, the back isn't. I'm using a Canon 350D, with a 75-300mm zoom. it's not particularly fast, but still works ok. Is this something I just have to accept, or are there settings that I could use that would solve this? Basically, without a media pass, I can't get close enough without using the full zoom, so advice such as getting closer won't work.