Another attempt with the D800E + EL-Nikkor 63mm f/2.8N, reversed on PB-4 bellows.
This time part of the circuit board on the back of a HC-SR04 - Ultrasonic Distance Sensor.
I am quite pleased with the results that I am getting with this setup, although so far I have nothing to compare it to.
I think I might try reversing the AF Nikkor 50mm f/1.8D on the bellows, to see how that compares.