As some of the other guys pointed out there are some mechanical requirements. If your machine is tight enough and can mechanically handle that kind of precision then it really boils town to tuning your print setting. The thinner the laters the more precise your settings need to be. Under .1 and things start getting more and more difficult to tune. Inrun a makergear m2 and someone did a print once of the yoda head at .02. It was really crazy. There were no layer marks at all. I havent ever really bothered to giobelow .1 because there is no real need for any print i have done and i actually want to have something completed within a week lol.