I want to buy a canon 70-200 f2,8 for my 40D but am put off by recent reviews stating that the sensor of a crop camera is over loaded by this lens and therefor the images are not as sharp as they would be as on a full frame body. Is this true? I would prefer to test this for myself but since I purchase my gear from B&H it is hard to do, and I do not feel it is right to take up the time of the folks at my local camera store when I will not be buying from them. So if any of you have an opinion on this I would certainly like to hear it. Perhaps it's time to move to full frame.

Huh?

The 70-200 works quite well on a 40D. In fact, every Canon telephoto that I have tried works very well on a 40D. Images are crisp, focus is quick, and the 1.6x lens factor gives me a little more reach that sometimes comes in handy.

The only downside to using the 70-200/2.8 is balance -- even with the battery grip, the 40D is much lighter than the 1-D series cameras, and the combination balances differently. For this reason, I like to put my 40D on my 300/2.8 and put the whole thing on a monopod. Great combo.

When I look at the photo's on pbase taken with a 70-200 f2.8 lens, I can easily tell which pictures have been taken with a full frame camera and which have been take with a crop camera without having to look at the efix data. The files from full frame are far superior. Check it out! I use a canon 200mm f2.8 prime with my 40d and that lens rocks on a 40d, but I don't think the zoom does.