[irtrogdor]

I use a sharpener similar to the one you posted, except mine is hand-held. All it does it make sure that every time sharpener hits knife its at the same angle. Anyways I use that to get an edge on my knife and then use a hand-held fixed angle ceramic sharpener to get it really sharp.

If you have to do it by hand however, the optimum angle is in between 19 and 20 degrees, which is practically flat on the sharpener. I like to use a Ez-Lap, which is just a piece of steel with diamond flakes or dust on the sharpening surface.