hello all

i own one canon 40D and i was planning to buy the 100-400mm IS lens but one friend of mine told me that it might not work well together.he said that this type of lens (big ones) works at it's full potential on higher quality bodies like 1D or similar ones.

can anyone tell me if this is true? can the small battery from my 40 D be to weak to "spin " this big lense?

thank you very much