This is the advantage of the detachable lens. With Z1 and the P+S adapter you're stuck with setting the lens to telephoto, where the F-stop is 2.6, and the T-stop may be 3.0, or who knows what.

I don't know how good is the relay/macro prime that is used for Canon with the P+S 35 mm adapter, but it would not be hard to do some prime lens modification to get pristine picture quality without color aberation and save 2 F-stops over the competition.