SHOOTING THE TIP OF A BALLPEN. I reversed my 50 mm 1.8 II (I manually fixed the aperture at f/5.0, my presumed optical sweet spot of the 50 mm),
then taped it to the front of my 100 2.8 USM macro. The minimum focus distance was circa 20-30 mm, and that results into unbelievable magnification.
The lens combo was mounted on my 7D and all was supported by a 410 gearhead and 455B tripod. Lighting was available light coming from a window to the right.