An answer to my question ?

I have just purchsed a new 16-35 f2.8 usm lense to go with my 1DS mk II as well as on a 400D.
When it's at the widest 16mm under low light conditions you can see the shadow of the lense hood, if I use the flash indoors the same happens.
Its ok at the 35mm end.
Also when on AF the shot always looks blurred through the eye piece but the pictures are clear.

Am I missing something here, none of my other fleet of lenses do this.

Many UWA lenses will produce a lens hood shodow if used with the onboard flash. Try using an external flash on your 400D.

As for clear pictures with a burred viewfinder image, that sound like the viewfinder diopter needs adjusting. Try adjusting the viewfinder so the focus diamonds are sharpest while the lens is pointing at a blank wall and grossly unfocused.

Thanks, I'll try it with an external flash soon.
Also I feel such a dick head, I had forgot about the diopter, you were correct.
Sometimes the most basis things are the things that catch you out
I quess thats why we need forums
Cheers

Also, make sure that you have the hood on correctly.

Which hood are you using on the 16-35? I don't notice it on my 1Ds at all.