I have a bit of a problem, I think

5D, C/Y Zeiss 50mm f/1.4

AS you know, I have a C/Y Zeiss 50mm f/1.4 lens and I use it with my 5D and EOS 3 with an adapter. Now, this adapter gives me focus confirmation, which, in addition to the focusing screens I purchased, help me manually focus this lens with my Canon bodies.

I began to have suspicions about a problem when I saw this image:

5D, C/Y Zeiss 50mm f/1.4

The foreground of the image is in focus, as shown below:

And, if you look at the image itself, above, you’ll see that the horizon is very soft. Now, I know this image was captured at f/1.4, so I figured I might have just not focused on the horizon.

When I use the lens to focus close, I get what I expect:

I have a boatload of shots where, even at f/1.4, I get what I focus on. But then we get the image at the top of this post, which I’ll reprise here.

5D, C/Y Zeiss 50mm f/1.4

As you can see, this image isn’t that far away (15-20 feet) and I vividly remember focusing on the door itself (in fact, I also remember getting focus confirmation on the door itself, near the latch and lock). Take a look at the latch and lock:

Latch and lock

Obviously not in focus. Take a look at the foreground:

So, either I mis-focused or the lens is front-focusing or, what? Could the adapter by off in a way resulting in the focus getting more and more off the further away the focus target is from the focus plane?

This image was captured at f/2, so I did have a narrow plane of focus, but I don’t think I would end up being that far off. And I didn’t think the focus shift at f/2 would be that great.

Focus shift? Adaptor issue? I know I have some testing to do, but on the Contax body, I don’t have any focus issues (below is an image shot with the lens and the proper body). I know the distance is different, and I have tests to do, but . . .

Contax RTS II, Zeiss 50mm 1.4

So, any thoughts about how to test this issue?