Modeling recessed lighting (cans)

[buttonsaretoys]

What's best way to model a can with SU and V-Ray? In SU, I drew a circle and then "pushed" it into the ceiling 9" or so and dropped an omni-directional light in. It worked, but the lighting doesn't look realistic around the edge of the circular opening in the ceiling. I was hoping to see the opening, but instead it was lit white in that area, even though you couldn't see the light source from the camera location.

Is there a better way to model a can? I'd really like to see its aperture when the light source is occluded.

Thanks in advance,
Rich