Lens sharpness vs. camera shake

[Robert Soames Wetmore]

I'm not trying to be a wise guy here, but aren't the tree tops moving a fair bit even on still days? What were your shutter speeds? (And sorry if you've already addressed this point - I'm a bit behind on reading the digests.)

[...]
Getting sharp images with long lenses is an exacting task, much more
difficult than meets the eye. Forgive the weak pun. I've been taking >shots of tree tops recently with a Sigma Apo 400/5.6. They are not >particularly sharp although I used the highest shutter speed I could. >Its hard to decide if the images are fuzzy because: the lens is not so >good wide open, the shutter and mirror vibrated the camera on the >tripod, the lens is not so good anyway, or the camera was not properly >focussed.
[...]
Don Williams

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