This has been mentioned a couple of time to me and I still can't really get my head wraped around the "why" of it... So, when you get a zoom lens (say a 35-80mm for example) you aren't going to have as good of a DOF as you would with a fixed-focal length lens unless you're willing to shell out some serious dough for a high quality piece. Correct? If so, then why? If you can't tell, I'm still shopping around for a new lens. Thanks.