Does anyone have this lens? I was looking at possible lenses for my T1i and I found this lens. Is there anyone who can tell me how well this lens performs? I've heard that it's more aimed towards the video users. But I want to use it mainly for photography, but I heard that when using this lens, the viewfinder becomes useless at around f/4 and above. I was looking at pictures and I was amazed at the IQ. Sorry for asking a lot of questions.