I held this lens on a new EOS1V@ Photo + LA in June and it's sweet.

Probably your arms if you don't have a monopod!

$10k will weaken your wallet, but it's worth it if you shoot super tele all the time

I didn't shoot any film with it, but it is hand-holdable with the IS turned on. I could bulls-eye on a target and it held steady. Simply amazing technology!

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None

Can't fault it. Great optics up to 1200mm and low (down to 1/60 sec) shutter speeds with high hit rate on sharpness. IS works great at 1200mm.

My arms when hand held!

Outstanding lens. I can get shots at 1200mm at low shutter speeds (down to 1/60sec) on still subjects that required all sorts of stabilizer bars on the old 600mm to keep it steady. Optically I believe it to be slightly better than the old 600mm when I do side by side tests using the 2x teleconverter. The difference, however, is very slight and almost unnoticible using the 1.4x TC or the bare lens. It is lighter than the old lens and every pound helps. Build quality is excellent and as good as the old one. The focus lock buttons are a great help especially when using the 2x TC which limits focus to the center with the EOS 3. The reduced minimum focus distance from the old one is a great help. IS is a winner for shooting out of a car window!!!

Overall verdict: if you have the cash and love wildlife photography then buy it!

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I own the 600mm F4 non IS as well, have used the 400mm F2.8; I own the 300mm F2.8 IS and many others.

The world's premiere super telephoto lens. Delivers sharp images with 1.4X, 2X and even stacked TCs. Have made sharp images at 1200mm at 1/45th second and at 1/125 second with two 2x TCS! Focuses fast enough with 2X to photograph large birds in flight.

Most units do not rotate smoothly in the tripod collar when the lens is mounted.

Do consider the fact that I have been a Canon contract photographer since 1995. But know that my comments above are totally honest and unbiased.

Customer Service

Excellent

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Canon 500mm f/4.0L IS lens and several smaller Canon IS lenses.