Finn M: " And why make a big and expensive f1,2 lens if you have to step down to f2,8 to get sharp pictures?"
Because people buy it at a ridiculous price and they just will not let go of it once they managed to get hold of it.
Canon makes lenses to sell them. And this particular lemon seems to have a lot of takers. Go figure!
Probably you can now model the optical characteristics of this lens in PP just like you can model amps and guitars with electronic gadgets at a fraction of the price of the Real Thing.
Or can you? Anybody know of a digital lens simulation software?