Kaleinar-5N or Калейнар-5Н 100/2.8 MC

lens design from http://allphotolenses.com

This lens has good reputation, it always compared to Nikon 100/2,8 E series.

Minimum focus distance is marked 0,8m, here's sample at closest focus

cropped

Nikon 50/3,5 auto micro pre AI

This lens is cheap among macro lenses, but the quality of it isn't cheap.

cropped one

Infinity test

crop from above