Human beings, of course, have tremendous accuity, but they do not and never did have the accuity of an eagle, and it takes an "eagle eye" (in the form of a 2X or greater lens) to give it to you on a two-dimensional surface.
Almost every experienced artist on Earth can differentate between detail paintings that required the use of a prosthetic and those that didn't. So can you.
Plenty in this case meaning enough to demonstrate that freehand drawing and painting are skills that can be taught, at least given a suitably talented and motivated student.
Human beings, of course, have tremendous accuity, but they do not and never did have the accuity of an eagle, and it takes an "eagle eye" (in the form of a 2X or greater lens) to give it to you on a two-dimensional surface.
You assume the artist is trying to trying to reproduce accurately the details of objects he has never seen except from the vantage point implied by the painting. That's absurd.
You ignore the fact that most artists have perfectly good legs, and can thus get up and examine things they need to look at closely. They also have imaginations which can make up aesthetically pleasing stuff to fill in the details they can't see.
A good artist will familiarize himself with any subject he intends to reproduce accurately. He will be able to remember what an obliquely-viewed object looked like, even if he cannot see it terribly well. And if the details as remembered don't strike his fancy, he'll supplant them with his imagination.
Almost every experienced artist on Earth can differentate between detail paintings that required the use of a prosthetic and those that didn't. So can you.
The tracing-paintings I've seen haven't impressed me. Perhaps you could point me to some better examples.