Summary: Lens lock is for transporting only, but then again no lens creep. This lens is big; a little more than the diameter of a Pringles Can and about 8" long.
Pros: This is a 4 Egg Lens* (see cons) Has AF/MF, IS, and USM**. 70-300mm Telephoto Zoom Lens No lens creep.
Cons: *I bought it on Black Friday, Tuesday it was out of stock and they dropped it $100. It was back in stock on Thursday. -2eggs for New Egg **USM is pretty loud. Lenses rotate as you zoom and focus.
Summary: This lens should be avoided by those with high standards of contrast and sharpness, usually found in better Canon lenses. Small details, object definition and color are subdued. The overall image needs much more manipulation in Photoshop to reach the level that the simple EOS 75-300mm IS lens displays. Portrait and action photographers will benefit from the advance technology in the IS and iris diaphragm. I'm sure there will be a version 2.
Summary: If you search for reviews of this lens you'll find that the majority rate it poorly - take those reviews seriously! The only thing this lens has going for it is that it is small for a lens with this range. On the negative side, image quality is poor and when zooming the lens quickly reaches a minimum aperture of f/5.6 - this means it either needs a lot of light or high ISO to get a sharp exposure.
Not worth the money, buy the 70-400 f/4-5.6 IS L lens instead
Mr. Shaun Pugh, Amazon
1 April 2012
Summary: I'm still deciding which lens to buy so I hired this lens and the 70-300 f/4-5.6 IS L lens and used them both for a week. They are both a very similar price, the L lens has a slightly wider aperture, but weighs more. Otherwise at least on paper they are fairly evenly matched. One of the benefits of hiring a lens is that you see how the lens would be after a couple of years use - the copy of the DO lens I had was floppy, and extended under it's own weight quite easily.