I've never seen a Rodenstock Apo Artar. Also the lens that I'm still kicking myself for selling, and would be a great lens for the 11x14 shooter, was the 14" blue dot Trigor. Mine was the American model not the Swiss Kern model. It covered my 8x20 with slight movements. But was way sharper than my old 1903 Dagor. It was sort of like.. covered like a Dagor but was sharp like an Artar. Of course the Trigor was a coated lens where as my Dagor isn't. Sorry, I didn't mean to get off topic. This has nothing to do with coverage on a 12x20. If the original poster wants to use the 19" Artar for close up stills in-studio then he just may have enough coverage to produce very sharp photos. But for using it as a landscape lens on a 12x20 at infinity, he may find that the corners will get pretty mushy even stopped down. It would be interesting to see the results in both situations. Artars are great lenses and if it doesn't meet your needs you'll have no problem recovering your investment. I hope it works out well for you. Also let me add that once you compose on these huge ground glasses you have entered the abyss of ULF for which there is no return.