I have herd from a cople of sorsess that ussing ex tubes with telephoto lensess and a x2 is better than using 2 x2`s and a 300 mill lens on a cannon 350d. I dont have much money to my name and I love sitting in bird hides and taking nature shots. The other thing is I am never satisfide with some of the shots that i do get there ether shook or out of focas slightly.....