Yes, medieval illuminated miniatures have incredible detail. The thing to keep in mind, when looking at illuminations for Books of Hours, for example, is that most of the time, the books were only about 10x15 cm, so if a painting looks detailed when blown up to full-screen size, it must be really tiny in reality!

For example, while looking at a Book of Hours on Friday (I forget which one, since I looked at about three), there was a scene called "War of the Angels" which had dozens of tiny naked angels flying about. Each angel was about 1 cm tall, and each had a face and genitalia. (When my mentor observed the latter, that made a whole bunch of other people suddenly want to see the book! :^D)

I love detail work and am quite good at it, but that awes even me!