Well I have finnaly managed to do some sort of rig to my butterfly, at the moment the DOF doesnt seem to work correct. I am using the Mental ray "physical lens dof" the butterfly get a nice and small DOF effect but the plane that I use as a background is not effected at all. :S If you have any good ideas regarding the texture please say so. And yes I dont plan to use that background as my final, it is just a test.