I just saw a twelfth century painting and thought about how much it was of it's time: https://upload.wikimedia.org/wikipedia/commons/6/69/Transfiguration_of_Christ_Icon_Sinai_12th_century.jpg But who was the first known painter whose paintings went beyond the sort of cartoonish look that even the best were producing back then to produce something that looked like it had almost the quality of a photo? The earliest one that comes to mind for me is da Vinci in the very late fifteenth century, but of course artists much have been pulling that off long before him.
Sorry if this comes across as snarky or something, I just couldn't think of better ways to phrase it.
Buonarroti was probably the most consistent and most photo realistic. His sculptures were probably also the most realistic. But the Greeks were generally the first to accurately depict the human representation. Unfortunately the only mediums to survive since 500 A.D. were their statues.
However I think your trying to find the word Naturalism. In art, what you're speaking of is Naturalism. That dates back to 14th century.
The painter David Hockney has advanced the theory that some very famous realistic painters, like Vermeer, were using a camera obscura to project an actual reflected image onto a canvas, and using that as a guide to painting. If true, that could be defined as "photorealism".
