Craigslist is a dangerous place. While reading a post in the Fuji forum about the Zeiss 50mm Ultron, I ran across a craigslist posting selling a copy of this lens with an Icarex body. Met up with the seller, and after a little negotiation, I welcomed another lens to the stable.
From what I can gather from the web, this lens is a Voigtlander design that was given the Zeiss label when Voigtlander was purchased by Zeiss. It has a concave front element (again, German engineering answering a question that was never asked). My copy has an M42 mount, but it was also available in the native Icarex bayonet mount.
This is my first piece of German glass. I don't count the Voigtlander 58mm Nokton I owned several years ago as it was a Japanese built and designed lens. It's a hefty piece of glass, but it's also the smallest 50mm I've owned (that makes it the most dense) short of the Nikon 50mm f/1.8E pancake lens. The aperture ring is clickless, which makes it difficult to set the aperture on the fly. Filter mount is an Icarex B50 bayonet (don't confuse this with the Hasselblad B50), which makes filters and hoods expensive. There is a B50 to threaded 52mm adapter available.
The lens is wickedly sharp, especially in the center. Contrast is strong (is this the micro contrast that every talks about when they discuss German glass?), especially in bright sunlight. Focusing is relatively easy, although I usually find myself reaching for the wider aperture ring instead of the focus ring. Both rings are about the same width and because of the small size of the lens, are close to each other. Nothing that more use won't be able to correct. There isn't that much CA, which is a pleasant surprise for such an old lens.
Bokeh is nervous though, and can get a bit swirly under the right conditions. It's a look that I find a little disturbing (does it make me nervous?). Flare is also very weird, with a rainbow curve (possibly due to the concave front element) and reduced contrast. It's prone to this if the light source is outside of the viewfinder, but not when it's visible in the photo. Veiling flare is a problem, with even blue shirts showing quite a bit of glow. There are only five aperture blades (that overlap in the most complicated pattern I've seen), leading to pentagonal highlights. The pentagons have rounded corners and fuzzy edges, so they're not very distracting.
|Rainbow flare, light source up and to the right. Contrast adjusted in post|
How does the lens compare to my other "normal" primes? On the plus side it has the most contrast and is the sharpest wide open across the frame. On the minus side it has the worst bokeh and flare characteristics.
Back to the Voigtlander 58mm; the IQ of the Ultron reminds me of that lens, although the Zeiss is sharper wide open. I wonder how that lens performs on the Fuji? I sold mine because normal isn't really a range that I like on an FX body, not because of the IQ. I've ordered an M42 to Nikon F adapter as I'm curious to see how the Ultron performs on an FX sensor.
So now I have a surfeit of ~50mm lenses. Which one to sell?