Hi all! After much deliberation, I have decided to upgrade my camera from my current Canon T1i to the Canon 7D. However, rather than jumping right into a body upgrade, I was told that upgrading my lenses first is the best way to go. So I have been scouring Amazon in search of all the lenses I wanted to add to my wish list so that I can eventually start buying. I do, however, have some questions first... if anyone can answer them! I noticed that the abbreviations that marks top-of-the-line lenses from the 3 mentioned brands (Canon, Sigma and Tamron) are Canon - L, Sigma - EX, and Tamron - SP. Feel free to correct me if I'm wrong. So these are the only lenses I looked for amongst the 3 brands. Most of the lenses I have my eye on are the very (expectantly) expensive Canon L series. My questions are this: 1. The difference in quality and glass between the 3 brands - what is that like? For instance... would a Canon series L lens give the same quality photo as a Sigma series EX lens? I've noticed that the Sigma EX and Tamron SP lenses are significantly cheaper in price in comparison to the Canon L lenses, but if they don't produce similar quality, what would be the point on upgrading to those? 2. My current lenses - would they mount to a Canon 7D body? They are listed in my signature below. 3. If I begin purchasing lenses now with the higher quality glass - should I worry about THOSE being able to mount to the Canon 7D when I do finally upgrade? Any help would be appreciated. I apologize if I have repeated this topic and it's been discussed in the forums before. I swear I did a search before posting. Thanks!