How to increase circle dof samples in 4.11?

Development Rendering
#1

Hi everyone,

I saw on the new feature list that you can increase the circle dof samples count but I can’t find how.

Any idea?

Thanks a lot in advance
Ben

#2

Same question for 4.15
How to achieve smopoth bokeh?
At the moment I have this:
d9dafb3b71a87f22867993043b2b6bd1c84568d5.jpeg