I had recently found my macro extension tubes and whilst I knew what they did to the Micro-Nikkor 105mm f/2.8 lens I have, I had never tried them out on the 85mm f/1.4. Result? Bokeh you want to eat!
Read the full explanation of this hour at the park here:
Nikkor 85mm f/1.4 AF D
20 & 36mm extension tubes
Close-focussing distance reduced from 85cm to 14.5cm