I have a klimsch apo ronar 600/9 and -Good God!- it's heavy. But nice. I guess it'd cover 20x24". Unfortunately, just about the only camera that can take it is my (very solid) 8x10 metal cambo. I don't think you'd want to put it on anything wooden, frankly.
Anyway the quality of these lenses is generally very good. The circles are generous to say the least.