I've got the Canon 1000d and am looking at getting a new lens. I had this idea in my mind that I should buy for the future so I've been getting L series lenses where possible. This is because I plan to upgrade to a full frame camera in a few years time. What I was looking at buying was the Canon 24-105mm L lens. The issue I've got is that because I do not have a full frame DSLR I would not the the wide 24mm it would more likely be around 36mm. So my other alternative is the 18-200mm which would give me a wide angle but it would not work when I upgrade my camera. What would you do?