While considering the buy of a focal point it is valuable to go to tests on pixel-peeper.com for photograph rendering and on photozone.de to see the tests in the lab. It's in English however to see the designs ...
This gives a considerable measure of extra decision criteria ...
Accordingly the jump full gap and the bokehs among Nikkor and Sigma are talking.
Three pictures taken from pixel-peeper for correlation, the third to demonstrate that with a full scale focal point we can accomplish something different!
Photo1: Micronikkor 105mm
Photo2: Sigma 105mm
Photo3: MicroNikkor in show Tubemate Videoder Snaptube