adhocphotographer said:
58mm???? A bit of an odd focal length no? Do you think they use 58mm as it means mechanically/physically it is easier to have better IQ? Or is there some historic significance I am unaware of?
I bet the reason is technical, just like the new $4000 Zeiss is a 55, not a 50.
Bear in mind, though, that focal length and aperture are often rounded when stated.
For instance, if you look at the patent below, the 14/2.8 is actually a 14.17mm F2.89, and the 35/1.4 is 35.50mm F1.45. And I've seen worse discrepancies. Your 50/1.4 may actually be, say, a 53/1.49... Nikon could have called the lens a 55 or a 60, maybe they just decided to be more accurate about it.
http://www.canonrumors.com/2013/10/patent-canon-35mm-f1-4l-ii/