[Zig]

Let's have a look at the bottom corners of these shots then. We'll start at the bottom left corner:

Canon:



Zeiss:




And now tracking across to bottom right corner...

Canon:



Zeiss:




It seems as if the Canon struggles of course but let's bear in mind a couple of things: the Canon 16-35 at 24mm here is with an aperture of f9: thus, arguably I may have strayed out of safe hyperfocal territory and the lens may merely be exhibiting my own error in taking the shot. Also, remember that we are using a full-frame sensor here on a camera with 16.7 MP files. Of course, the Zeiss is a prime lens, whereas the Canon is an engineering feat in itself: a fast, constant-aperture, highly improved(upon the Mk1 version) collection of superwide and wide focal lengths...some degree of softness is to be expected. When you see the next few crops, you'll also see the Zeiss itself has softened ever so slightly at the corners. Mind you, note I have been slightly kind to the Canon here,, as I've not included the extreme bottom-right corner...just in case I had included foreground detail that was out of focus naturally at this wider aperture: the Zeiss, remember, has 3 more mm of focal length and is at a smaller aperture of f11.

So let's see if things look any different along the right-hand edge:

The Canon, upper edge right:




..and the Zeiss, upper edge right:




As you can see in the crops above, then, it would be easy(and missing the point) to just write off the Canon. This would be unfair: you can see that the Canon has very little chromatic aberration or colour fringing at all, if any. Also, this edge is not exactly the "mush" often described by some users(or detractors)...it's just that the Zeiss is ridiculously adept! The Canon's edge performance in the real world is in fact a whole lot better than many a prime...and would improve a bit further if we saw the same shot with the Canon at f11. I know it's an expensive idea, but if the 16-35mm f2.8L MkII were on an APS-C body, you'd be getting rid of the edges and corners anyway. Yes, this defeats the object, but it is always a good idea to get good glass first: when I still had the 350D I started to save for and buy my L lenses, knowing that at some stage in the future I'd be moving to full-frame. The 16-35 on this format was something akin to a 25-56mm equivalent(if my maths is right).
In Part 3 I'll show you the relative central detail and sum things up.

[Toad]

Always game for a bit of pixel peeping.

I prefer the Canon in the edge shot - but let's face it - it's a pretty subtle advantage.