A good friend of mine recently purchased a new EF 400mm f/4 DO IS USM mk II to use with his bird photography. His plan was the replace his EF 300mm f/2.8L IS USM mk II with this new lens for the lighter weight and added focal length. The first copy ended up being disappointing and after a trip to the Canon service center it was determined that it was not up to speed so it was returned and a second one was ordered.

As fortune would have it my friend got his second copy of the DO mk2 and met me at the airport when I got home from a recent trip. I spent the last two days shooting with it on both the 7D mk2 body and the 1Dx body with the bare lens, 1.4x III and 2x III.

The second lens that he received definitely performs better than the first one. It is definitely small and light and performs like a dream in terms of handling and ergonomics. AF is extremely fast on both bodies but I could definitely feel an improvement on the 1Dx, especially when the 2x TC was in use.

With the first copy of the 400mm f/4 DO IS USM II the Canon service center determined that a microfocus adjust setting of -18 was necessary to get optimum focus on the 1Dx. Everyone that either one of us spoke to at Canon agreed that a brand new lens should not need MFA. With the second lens we checked MFA on both the 7D2 and 1Dx and the results were much more in line with our expectations. In all cases little to no MFA was needed.

In my normal shooting I don’t use a 2x TC very often so shooting at a max aperture at f/8 took some getting used to. It really made me realize how much I use the off center AF points and forced me to be very careful when doing focus and recompose. At 800mm the DOF is typically very thin and it is easy to lose critical focus on the eye. I did notice a real tendency for he AF to search and this is where the AF system of the 1Dx had its biggest advantage. The 1Dx is able to drive the AF faster and while both cameras would search for focus often, the faster focus speed of the 1Dx meant that there were less missed shots from waiting for the focus search to complete before locking on.

The latest IS also is a big benefit. My most used lens is the EF 500mm f/4L IS USM and the IS on that lens is fairly old, I believe only 2 stops. Canon has made some substantial improvements on IS since then and it really comes in handy for my style of shooting. I rarely use a tripod and many of the birds I am interested in don’t typically come out in the open for good sunlight… Every extra bit of stability is appreciated. With the 2x TC you are starting out at f/8 so shutter speeds area already challenging at the ISO settings I like to use (typically 1600 or lower) so again the new IS really is appreciated.

Now to get down to the most important part, how is the image quality? In the past I owned two different EF 400mm f/4 DO IS USM mk 1 lenses. I really wanted to love that lens and I did really love the size and weight but both times the image quality just wasn’t up to speed with my other lenses (300mm f/2.8 IS and 500mm f/4 IS). The contrast wasn’t as good and while I was able to get decent results with both of the old DO lenses it pretty much required pretty much filling the frame with the subject and more post processing than I did with my other lenses. When the subject was smaller in the frame I never could get comparable results to what I was able to get with my other lenses with relative ease. This was most pronounced when shooting in low contrast situations and back-lit situations. In beautiful light and at close range the old DO lens was just fine.

Now with the new version (EF 400mm f/4 DO IS USM mk II) I definitely see a substantial improvement over the old version across the board. Contrast is better, overall sharpness is improved and the lens does seem to perform more consistently when lighting conditions get more challenging. However, I still don’t think it is quite at the same level as the other len