while I'm gnawing at this topic (and a carrot) I thought you might find this interesting:
I like to use wide angle lenses on interior subjects (like at workshops).
often I don't have enough width (28mm width on this occasion)
I normally work at a fixed distance to my subjects even if moving around ... so picking a number like 3 meters to dial into a manual focus lens and setting f5.6 you get an interesting DoF result ... plugging this into a calculator I get:
which even if you haven't worked with the lens will show you that its good for getting all the stuff in the scene and gives a nice gentle fall off to the background while keeping close obstructions from getting too much attention in the foreground (as they may walk in or wave at the wrong time)
nothing is faster focus than fixed focus ... ask a street shooter