<p>JDM von Weinberg:</p>
<p>"EF 100-400mm f/4.5-5.6L IS <strong>II</strong> USM = $2,199.00<br>
EF 100-400mm f/4.5-5.6L IS (I) USM = $1,699.00"<br>
While I don't know what Antonio is paying for his Antarctic trip, most pay $10K+ if traveling from the US (not including airfare), which is why it is a once-in-a-lifetime experience for most.<br>
So if he's thinking of selling the 70-200/2.8 I'd suggest he buy the new 100-400L. As others have noted, it appears as though it will be about as good with the 1.4x as the old one was without.<br>
I photograph a lot from boats ranging from about 70 feet to much smaller zodiac-style ones on often fairly rough sea water on a frequent basis. I think the twist style zoom's better for shooting on a boat (and while at antarctica there are landings, there are also typically times when one shoots whales and other marine mammals from zodiacs, and opportunities for photographing pelagic birds from the ship itself). The reason I feel this way (and I owned a copy of the push-pull 100-400 for awhile) is that you can securely brace yourself and zoom without shifting your hand position with the twister, while pushing and pulling requires moving your front hand back-and-forth. Turning a ring just seems easier to me, and as I say, I've used both.<br>
Antonio, I use the 300/4 on salt water a lot and I've been very happy with it. Good quality, it has survived bumps and drops without a problem (well, the built-in lens hood is a mess, but we'll ignore that, stuff happens when you drop things and it's just the hood's locking ring). But I'm switching to the new 100-400 for my boat work.<br>
Remember, you're going to be in a harsh environment, so you want to avoid changing lenses as much as possible. If you can possibly take two bodies, one with something shorter, then the 100-400, the only lens-changing you'd probably need to do would be to add/remove the 1.4x depending on the situation.</p>