Dead leaf - NEX-5N & Schneider-Kreuznach Componon [Durst] 50mm f4 Enlarging Lens. Click for larger.
Of all the enlarging lenses I have, the Schneider-kreuznach Componon (Dusrt) 50mm f4 is the most elaborately built. The entire lens barrel was made of brass and chrome plated. It also sports a 15-blade aperture. Interestingly, at maximum aperture of f4, the aperture blades are not hidden. I suspect the lens is capable of f2.8, but is restricted to f4 as the maximum. It came with both the front and rear lens hoods. Very beautiful and heavy, with excellent optics to match.