I was fooling around and came up with these different macro setups, proving that anything is possible.
Nikon D7100 with manual extension tubes and Nikkor-S 50mm f1.4 manual focus lens.
Nikon D7100 with Nikon F - M39 adaptor and Canon M39 extension tubes with El-Nikkor 50mm f4.0 enlarger lens.
Nikon D7100 with M42 adaptor ring and Praktica bellows with Jupiter 8 50mm f2.0 lens mounted on macro focussing rail.
Pentax K10D with Praktica M42 bellows and TT&H f6.3 six inch anastigmat.