The Canon 100-400 f/4.5?5.6L IS Mkii is a great lens to hold and to shoot. It’s a fairly versatile lens capable of great compressed landscapes, wildlife and other subjects where the reach is needed. This is not a gear-head tech based report. This is intended to be more illustrative of how this lens is easy to use with a variety of subjects.
The images shown here were captured with the Canon 7D Mkii. Some were also captured with the 1.4 and 2.0 tele extenders.

Compressed landscapes can work great for expressing your creativity. Here we see a southeast Washington wheat field panorama. I shot multiple images from left to right and stitched them together in Photoshop. The final result is just shy of 67MP. I can’t wait to make this a big print. About 24 inches tall by however wide it ends up being should do the trick.
I had the opportunity to take this lens to Steigerwald National Wildlife Refuge in January 2015. I wanted to photograph some birds and was able to find this heron who earlier ate a rodent of some sort. I also found a couple eagles and a kestrel.
Its ability to capture the fine details really helps show the little nuances in the feathers and grasses. It’s important to really work on your technique though. It’s way to easy to get blurry results, even on a tripod, due to camera shake when you’re not paying attention to keeping things steady.

I’d never seen a kestrel before. A friendly couple that passed by during my shoot told me what this bird was and thought it was so cool that I could get so close. This first shot is with the lens only on the 7d2. This second shot is captured with the 2x tele extender. When the extender is attached, it’s a bit less sharp, but the most notable issue is the lack of auto focus. There’s just not enough light coming through to use auto focus. You could use the contrast focus while using the live-view function but that’s just not very fast. It’s accurate, but if you need speed, don’t count on it. For this shot below I actually did use the contrast focus in live-view. I just focused on the twigs and then I switched it to manual focus and waited for the kestrel to land (he had taken off and returned several times). It worked out nicely. There’s not enough sharpness to go big with this photo, but I would do fine with letter sized or thereabouts. You see it here full frame as captured by the 7d2.

For this bald eagle shot I also used the 1.4x tele extender. It makes for a nice sharp image.
In the end, this certainly is a great lens. It’s a touch sharper than version 1 and if you’re on a crop sensor body like I am here you don’t even get to see the true edge performance of this lens due to the crop factor. But it certainly performs well on a full-frame body too.