So what's the deal with rotational zoom. Is it worse or just different? Plusses? Minuses? I realize that you can't use Petal type hoods, and figure that you would have to fix your CP every time you zoom in or out. I'm looking at the Tamron 28-75 f/2.8 XR DI, because someone is selling one barely used, and maybe I can get it cheap. But I notice that al the high end lenses don't rotate, and I was just wondering what the downsides were. Thanks!