I happened to see that a copy of the very rare Nikon 13 mm f/5.6 lens was for sale here. Both the design and price tag are pretty extreme. This article seems to suggest that it really is one-of-a-kind being that wide a rectilinear lens, but there are
plenty of wider counterparts to be found today (for example the Sigma 12-24), even with larger apertures.
What's the thing I'm missing here? Was it the first 13-mm rectilinear lens to be produced? Or is it made for larger format than 35 mm?