smooth DoF with yafray ?!

When i try to use the Dof in yafray i get really noisy pictures. Even strong AA can"t get rid of it. Is there any option I missed ?
this is the current result I get :
this is how i want it to be :
is there any way to do that ?

thanks !

Okay, I found one solution : -disable auto AA and set really high settings like 8 samples, 25 passes, and 0.005 AA treshold. It takes times but the result is better.