03-23-2013, 07:29 AM
I think the graphs are scaled so that rough visual comparison even between different systems is possible (with regards to choosing where the bottom cutoff level is, since they all start not at 0 but at some other value). That's the beauty of Photozone. That said, the spatial plots at SLRGear.com are, in my opinion, the best method of visualization, but they must be taking a magnitude more work to create.