Mustafa please read the Nikkor One Thousand and One Nights; it points out that Nikon lenses were designed by individuals as well. Leica doesn't hold the patents to hand calculated lenses.

As per that site in reference to the Nikkor 35mm f/2.8 its been thru 3 optical versions (perhaps 4?). I have all three versions, and vastly prefer the K/Pre Ai.