well, i just saw this thread and it reminded me of the reason i skipped learning DOF a long time ago. the renders just DONT RENDER. this is in yafray btw. I render a simple scene (one lamp, ray shadows turned off, 15 duplicated cubes) in about 1.1 seconds
then with DOF and random sampling (1.7 seconds)
then DOF and QMC instead of random sampling (cut off at four hours)
what do i have to do to get a decent DOF?