i must say your lucky to get shots of elk so easily, in michigan i have to travel well north to even think about trying to get shots like that, even with that i'd need lots of luck.
its just wierd at f/19 it should be really sharp.
a pic i took at a festival by my place, a mime of some sort trying to be a robot or something. Soooo sharp.
OK, that's just not fair... my 55-250 has never been, and will never be, that sharp. Are you sure you weren't using an L?
Can you post the settings for that shot?