For this analysis I will be using:

https://wpcalc.com/en/angular-size/

Germany (Stuttgart) When October 1972 The resolving power of the human eye is 0.0003 of a radian or an arc of one minute (1/60th of a degree), which corresponds to 100 microns at 25 cm (10 in). A micron is a thousandth of a millimetre, hence 100 microns is 0.003937, or less than four thousandths of an inch or 2.5 cm.

from:

https://www.guinnessworldrecords.com/world-records/smallest-visible-object/

Smallest visible …