Hi, I just experimented with the quality of the Canon 5D MkII. These are all the same photo...just zoomed in further and further.

boat16%.jpg
Photo @ 16%...Full photo shown

boat50%.jpg
This is @ 50%

boat100%.jpg
This is @ 100%

boat800%.jpg
This is @ 800%. I put this one in because I was impressed just how clear this is at such a high magnification.

By the way, these photos are of the jet boat on Sydney Harbour.