Quote Originally Posted by George Slusher
(For example, the difference between the 70-200mm f/4L non-IS and IS versions is $500; for the f/2.8L versions, it's $650. In both cases, the difference includes weather-sealing, as well.

But those aren't the only changes brought forward in the IS version. The optics were completely redesigned, a cicular aperture was used, and the minimum focus distance was made shorter.


The optics alone, in my opinion, account for a substantial part of the price differential over the non-IS version.


Quote Originally Posted by George Slusher
Few people would opt for an f/5.6 prime when they could get a f/5.6 zoom for the same price. The prime's image quality may be a bit higher, but its minimum focus distance is not as good as the zoom (11.8 ft vs 5.9 ft) and it weighs almost as much (2.8 lb vs 3 lb).


Although this is a choice that is made on an individual basis, I kindly disagree. Aperture and a "slight image quality improvement" are not the only determining factors in make one lens better than the other. In fact, I think that this image quality improvement with the prime is much better than just "a big higher".


For many photographers, the image quality advantage of the 400 5.6 L far outweighs its disadvantage of zoom versitality and Image Stabalization. Minimum focus distance, in my opinion, shouldn't be considered a serious disadvantage of the prime. Extension tubes can help you focus closer, but to put it in perspective, nothing will make your lens any lighter, or have better sharpness right out of the camera.