Cycles post process depth of field / defocus node

I’m currently trying to add some depth of field to a project with the defocus node. (Real DoF is too grainy for me.) I have an object in the middle of my scene that I want the focus on. How can I make the defocus node use the actual camera focus point? Is there a specific render pass for that? Thanks in advance.

Camera focus set to middle cube

Thanks. I had it set up exactly like that, but somehow it wasn’t working. Turns out I forgot to set the F-stop, haha. Thank you!