Blender for optical modeling II My question is similar to this question: Can blender be used for simple optical modeling? . 
I apologize for asking a similar question but I don't have enough reputation to comment on the original question.

Like in the original question I would like to view a scene through a modeled lens.
What I want to archive in the end is "real" out-of-focus blur (I am aware that one can play with the blur-nodes of the build-in blender cam, but I want to see the blur as generated by my specific lens)

As suggested by Liss' answer to the original question, I set up my scene using Luxrender as renderer as follows: (the answer contained guidelines, the specific details are my guesses of how to exactly set it up) 


created a simple lens (intersecting two smooth UV-Spheres, luxrender material glass or glass2 with IOR=1.41)
created a translucent plane (alpha 0.01) to act as film
set blendercam to orthogonal and placed behind film
as a test-object to be viewed through the lens I set a cube with a checkerboard pattern (to detect blurry lines when out of focus)


However when rendering the cube (or film) at distances to the lens where the cube should clearly be out-of-focus I still get a pretty sharp image.

From what I had understood Luxrender is very physically accurate so that tracing rays through a lens should result in blur. 
Is this correct? And if so, what am I missing to achieve the blur?
Blender Cycles is decent at rendering some optical effects.

This is an example of Total-Internal-Refraction simulation. This is done by placing a light source close to one end of some tubes set to a +IOR.


Source File for Fiber Optics

This is an example of (heart) shaped bokeh by placing a cutout in front of the Blender camera. (There is no lens simulation)



Source File for Shaped Bokeh