Quote Originally Posted by barzune View Post
Nikon came out with an excellent wide-angle lens, similar to the Zeiss Biogon in design (although with a slightly reversed formula), which you can see at http://www.mir.com.my/rb/photography...wides/21mm.htm .

Unfortunately, this gem cannot be used on any but the more pro-line cameras, that offer MLU. That negates the "reflex" advantage, requiring a separate viewfinder and zone focusing.

While this neither confirms nor defeats the "Achilles' Heel" premise, it does allow for an adaptation that works.

That lens was developed for the Nikon rangefinder cameras, then adapted to the SLRs. It was replaced with the 20/3.5 Nikkor UD, a big, heavy, and superb lens which does not require MLU. The Nikkormat Ft, FtN, and some others offered MLU.