Decided to share a few of my thoughts (and pictures) of the Canon 400mm f/4 DO IS (made September '05).
I searched for lengthy discussions about this lens and have not found any, so I would greatly appreciate any and every one posting their opinions on this thread. So here goes mine:
I love this lens! I've been debating the purchase for years and I finally found a KEH copy in Ex+ for $4k that looked to fit my needs--and boy does it. This lens amazes me every day I use it (3 days so far).
Now, to be perfectly clear, I have shot with both Nikon and Canon, and have used both companies' 300mm f/2.8 VR/IS, the Nikon 200-400 f/4 VR, the 70-200mms (f/2.8 VR/IS and f/4 IS), manual focus lenses (400mm f/2.8 Nikon, 500mm f/4 P Nikon, 600mm f/4.5 SSC, 400mm f/3.5 Nikon, 600mm f/5.6 Nikon, etc.), etc., so I have a good bit of knowledge on lens sharpness and build quality etc, etc. I am not someone who upgraded from the 18-55 IS to this lens, in other words. Just see my For Sale posts and you'll come across a lot of these lenses, here and on www.nikonians.org.
I must say I am the most impressed with this lens. It is so easy to use and I love the feel of it in my hand. It is so short and manuverable and so light! It is a dream to shoot handheld--I've used the 300mm f/2.8 IS, and that lens feels heavier and fatter. The 400mm was made to be used handheld and it shows. I love it.
Now, image quality is awesome, really second to none. I have used this lens with the 1.4 and 2x TCs (Sigma DG EX versions) and the images are tack sharp, even with the 2x TC! Really, tack sharp at 800mm f/8 (on a 1ds Mk II). Now, the shots I include today are from my 40D, but please email me for shots from the 1ds Mk II. They are simply astounding. Well, not artistically but in terms of sharpness.
Ok, enough of my ranting--I just wanted to put it out there that this lens is awesome. I do understand there were issues with older versions, but I rarely see (or have seen) it definitively stated that this is a good lens--and it is great. Please view the images below or email me for full rez samples. It would have helped me buy this lens sooner if I had seen samples like mine.
Please add your opinions to this thread.
Both shots below are with the Sigma 1.4 EX DG attached for 560mm f/5.6 on a 40D. Will post more pics too!