Hi guys, got a question about two brands. I've been using SONY A100 for two years and now I'm thinking about upgrading my lenses. Since I'm only a graduate student and don't have much money, I prefer those cheaper ones. And then I noticed there are two brands that I've never heard of: Rokinon and Tokina. Although I may not buy them eventually because they are TOO cheap, I'm still curious about them. Any one who is familiar with these two can tell me something about them? How about the quality of these two and what are their major shortcoming? I know they are manual lenses. Appreciate your help!