Carl Zeiss Distagon T* 45mm f/2.8 (645)

Pull a Contax 645 out of a wedding photographer's bag and there is a decent chance the 45mm is mounted next to the 80mm. On the 6x4.5 frame it works out to roughly a 28mm equivalent in 35mm terms, wide enough to hold a couple in their environment without distorting faces at the edges, tight enough that you are not constantly fighting clutter. It became a favorite wide on the system alongside the famous 80mm f/2 Planar, and the resale prices have stayed stubbornly high for years.

It is a Distagon, which means a retrofocus design built to clear the mirror box and still cover medium format at 45mm. Zeiss did the hard optical work here, and reviewers consistently praise the corner control for a fast wide. The center is sharp wide open at f/2.8, and there is enough field flatness that you can shoot architecture and editorial work without the edges going soft on you, though like any retrofocus wide it shows a little curvature and distortion if you go looking. Stop down to f/5.6 or f/8 and the whole frame tightens up beautifully across a 120 negative. The T* coating holds contrast and tames flare even with a bright window in the frame.

The rendering is why people put up with the rest of it. Color reads saturated but believable, the microcontrast gives skin and fabric a three-dimensional pop, and the out-of-focus background falls away smoothly instead of smearing into busy doubled edges. This is not a swirly, characterful bokeh lens. It is clean and well-behaved, which is what you want when the subject is supposed to be the show. As an environmental portrait wide it tends to get out of the way, and that is high praise for glass this fast.

The honest weakness is the system, not the optics. The Contax 645 was discontinued in 2005 and the autofocus electronics are fragile; a dead lens or body is essentially unrepairable now that Kyocera left the camera business. People still cross-shop it against the Mamiya 645 and Pentax 645 wides, both cheaper and more serviceable, but neither matches this lens for cross-frame sharpness or the Zeiss color. You pay a premium for glass that depends on a body nobody is fixing anymore.

There is no leaf shutter in this lens, so flash sync runs off the body's focal-plane shutter at its modest top sync speed; plan your fill-flash work around that ceiling. The 72mm front thread is the practical note. It is a common size, so a circular polarizer or a graduated ND for landscape work is easy to source, and when you stack one for a long daylight exposure, drop the filter factor into Zone Light Meter so the reading already accounts for the light you are killing before you trip the shutter.