On image tests my 400mm L 5.6 is performing significantly less sharp than my new 100-400mm lense. The only think I can think of that would have damaged the 400 was condensaton in the body from temperature changes. Shots are all tribod and cable triggered. No filters on either lens. This is of course cropped way in. Any ideas? The 400 is about 9 months old. Can it be cleaned internally?
@ebiggs1 wrote:"Those are the words of someone who never lost half of an important shoot because he failed to check out a new lens that turned out to need +9 points of AFMA."
And you would be correct.
Why would a person go into "an important shoot" without knowing their equipment. That is DSLR 101, my friend.
I never took anything new or untried into any critical job, ever. Matter of fact everything was/is covered by backup equipment.
I don't dispute any of that. I had just received the lens and hadn't had time to test it. It's a mistake I haven't repeated.
But the point (for this context) is that when I saw the result, I had to learn about AFMA and apply it to that lens/camera combination forthwith. The alternative was to waste time sending it back and trying again. And the reason I was able to solve the problem quickly is that AFMA just isn't very complicated. You take a series of pictures and see which one looks the sharpest at the operative AF points. Not many things in photography are simpler than that. Advising an experienced photographer not to try it, on the premise that he probably couldn't get it right, makes little or no sense to me. Especially since it's impossible to screw it up in a way that can't be immediately undone.
Bob fome Boston said,
"Advising an experienced photographer not to try it, ..."
But I don't know this? Experienced? Taking it for granted are we? 
"You take a series of pictures and see which one looks the sharpest at the operative AF points."
Now, Bob from Boston, we both know that is not how to do it. Don't we? It takes as Alan Myers suggested concentrated work done on a tripod. At a given target and range, carefully. Same, same each time.
It is a moot point because that isn't the OP's problem.
@ebiggs1 wrote:Bob fome Boston said,
"Advising an experienced photographer not to try it, ..."
But I don't know this? Experienced? Taking it for granted are we?
The thread has been going for more than 17 months, so it's a bit hard to keep track of the players. But I don't see lack of experience as a significant problem with any of them.
"You take a series of pictures and see which one looks the sharpest at the operative AF points."
Now, Bob from Boston, we both know that is not how to do it. Don't we? It takes as Alan Myers suggested concentrated work done on a tripod. At a given target and range, carefully. Same, same each time.
Maybe so, if you think you have to be absolutely certain of your choice between 0 and +1 or between +8 and +9, etc. But I assure you that you don't need a printed target or a tripod to see the difference between 0 and +9. So yes, unless you're a compulsive pixel peeper, that's exactly how to do it. There have been some good papers written on how to do it intelligently, like photographing a scene with objects at various depths, so that you can see them come in and out of focus. But that's just an implementation detail.
It is a moot point because that isn't the OP's problem.
I don't see how you know that, given the evidence presented.
Bob from Boston.
"And that doesn't suggest to you that one of the lenses may need AFMA?"
Ah, no it doesn't. They look like camera shake to me as nothing is in focus. If it were close enough for MFA to help, something would be.
This looks like MFA is going to fix it?
By all means give it a go and let's see.
Why he can shoot one lens and not the other is puzzling but its not because of OOF. At least I guess it isn't? Which is what all this actually is.
