Observation... Copernicus is 93 km in diameter. The crater in the old print is approximately 9.3 cm in diameter. So in 1850, that astrophotographer printed a detailed 1:1,000,000 scale lunar map of that region.

Today, we can download a 1:1,000,000 scale lunar map of that region by printing the following doc at 30"x30" page size: http://planetarynames.wr.usgs.gov/images/Lunar/lac_58_wac.pd...

Then, for apples-to-apples, you can trim Copernicus out of the modern print in a 13 x 16.5 cm rectangle.

Voila, a 160-year A-B of knowledge and techniques. :)

(Someone fix my math if it's off.)