Hai I have a Canon EOS 450d DSLR and am wanting to take great pictures of my kids. I am in awe of that great speckled effect - bokeh! Can someone tell me what kind of lens I would need for this and how much it costs? I have heard something about a 1.4 USM lens - could I use this, or is this type of lens just for professionals, or is it easy to use? Thanks!!