this effect seems to be broken on some maps.
you can try this out in the Vulcan space map.
Ships appear very blurry there and sharpen instantly when you turn the effect off.
another observation was, that objects became blurry when closing in on them so the effect just might be inverted somehow.
I dunno if it is a bug or not, but i didnt notice anything weird, at least not in this matter.
But i tell you, this effect (depth of field) on this game is terrible, i have it deactivated because it is so bad made that it is even embarrasing playing with that option activated. Same happens with the ambient oclusion. Two useless options that are implemented in this game like crap.
Anyways occured to me that maybe using other DX mode will make any changes?