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?
"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.
Yes, I looked at your website and see what you are photographing...
@nerys wrote:
Iahoot rockets. I can not useai modes as they invariablyie 99% of the time getborked by the background sky versus the rocket....
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... and I fully agree that AI Servo will not work for that. They are just moving too quickly and you are too close (it would be different if you were photographing a launch at Cape Canaveral and standing one or two miles away with a big lens... and that big rocket is accelerating to 17,000 MPH).
With a subject like your model rockets, YES... you need to pre-focus the subject as you are doing, then trip the shutter at the moment of launch. One Shot is one way to do that. (Manual focus would work, too... Or AI Servo in combination with Back Button Focusing).
However, your method with the B29 should be AI Servo. The technique you are using with One Shot... I've heard it called "bump focus"... simply works very poorly. It guarantees that a large number of your images will be mis-focused. I teach a lot of sports shooting seminars and have seen people using this method a lot. Invariably, they are stunned at how much more capable their camera is capturing moving subjects with AI Servo... I'm talking about "sports speeds" such as the airplane flying by at some distance, cars racing past, horses going over a jump, cyclists riding by, basketball players dunning down a court, etc..... Not "rocket speeds" up close... but general movement and in most cases from a distance. Even airplanes or cars doing 200 MPH and faster (so long as you aren't standing right next to them)....
... Above is one of about 1200 shots I took at a vintage race a few years ago, using the AI Servo technique I'm telling you about. I would estimate I missed focus on no more than 10 or 20 shots... and most of those were likely my fault, not the fault of the 50D cameras I was using.
Using One Shot for moving subjects is almost certain to cause missed focus issues. Unless the subject maintains the exact same distance while moving past you, focus will be off because the subject has moved out of focus before you can trip the shutter. And the longer the lens focal length, larger the lens aperture, closer the subject all make for shallower depth of field, which exacerbates the problem and calls for even more precise focus.
Using AI Servo and a single AF point that you work to keep that right on the moving subject - right where you want the camera to focus - is how you keep the focus tracking the subject and avoid it being distracted by the background. Doing this I sometimes shoot a split second burst and get four or five or more in-focus shots in a row...
The above series is a bit small here on the Internet, so you'll have to take my word that thanks to using AI Servo all three are in focus (actually there were more shots in this series... these are just the ones I show for composition and subject pose...all were in focus, none were out-takes for focus issues).
If I'd used One Shot and pre-focused on the jump, I might have been able to perfectly time a single shot... or I might have missed it if I didn't press the shutter release at exactly the right moment. But, by instead using AI Servo I got a series of shots, all in focus, including the three "keepers" shown.
Now, you generally shouldn't use AI Servo for "focus and recompose" technique (which is effectively what you're doing when you pre-focus for those model rocket launches), without also using another technique. That additional technique is called Back Button Focusing and it's very popular with sports shooters in particular, because it allows them to use AI Servo by default, even for focus-and-recompose. BBF separates AF control from the shutter release button and uses only one of the buttons on the back of the camera, under your thumb, to start and stop AF. More info about BBF can be found here in and article at the Canon Learning Center.
I gotta say, your and my 5D Mark II cameras really aren't the ideal sports/action/AI Servo models. The AF system of these isn't nearly as good tracking movement as some other models (such as my 7Ds).
But even the 5D II is capable of catching moving subjects at times, such as the redtail hawk at right. Actually I missed focus on a lot of shots of that bird, it was so fast, came so close and the 5DII just isn't fast enough.... But the bird was very cooperative, ignoring me and hunting right by me for nearly an hour of shooting. 
Finally, don't confuse AI Servo with AI Focus. I never use AI Focus... It's an automated mode where the camera is supposed to detect whether or not the subject is moving, then switch to using either One Shot or AI Servo, as it deems appropriate. Problem is, there is a slight delay while the camera is making up its mind... and sometimes it chooses wrong.
So I make my own selection: One Shot or AI Servo. And because I also use BBF, I use AI Servo by default, only switch to One Shot in certain circumstances.
I am pretty certain some of your problems are that you're using the wrong focus mode... If you were in One Shot at that airshow, shooting the B29, that almost guaranteed missed focus. Switch to AI Servo and learn to use it, and it can almost guarantee in-focus shots instead!
You might really find more useful info about the Canon AF system in three half-hour videos, starting with this one.
There still might be some issues with focus with your lens and/or camera... service or calibration might be needed... or proper Micro Focus Adjustment may help. But I think if you change some of the techniques you're using in some situations you'll get noticeably better results.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & EXPOSUREMANAGER
