Defocus Node edge artifacts: can be solved?

Hello to all,
I have this trouble: in the attached image you can see some edge aliasing artifacts on the object near the camera and not subjected to the DOF.

anyone knows how to resolve this?

thanks!
http://www.aardolino.com/test1.png

I think the new 2.46 Z-Mask node/function is designed to help with the edge wher ethere is a great Z difference.

No, the purpose of Z-Mask is to better composite things that would not composite well using a typical alpha-over or z-depth based composite (for example: fur). It has nothing to do with DOF specifically.

To eliminate artifacts from post-process DOF, you need to separate out objects of substantially different depths (especially separate objects that will be in sharp focus from objects that will be blurred) onto separate render layers, and then use an alpha-over node to recombine them after applying DOF to them separately.

You donĀ“t have the preview option enabled in the Defocus node, do you? Cause having that option enabled produces significant artifacts.

@jpbouza: no preview enabled
@Cessen: thanks, this is the more logical way, will be adjusted in further?

thanks to all

play around with the threshold(set it to 0?), you might get a softer looking image, but at least it will be artifact-free.