This video shows how the Voigtlaender Nokton 42.5 renders out-of-focus points of light at different f-stops. I tested it at the closest focusing distance (0.23m) and at 0.50m with f-stops from f/0.95 to f/5.6 (including half stops). There was no filter in front of the lens. Recorded with my GH3.
You might also be interested in this lens breathing test: vimeo.com/72766834