strange DOF

Hi, i’m playing with depth of field but i get very strange results.

The image above is from my project, The problem is the strange line between in focus and out of focus regions…
I’m really a noob, what i’m missing?

[attachment file=“dof.JPG”]

[attachment file=31110]

Hey Fabio,

I’ve seen similar issues on laptops when they haven’t been plugged into power, but I cant say for sure whats going on. Could you send your project into ?