The Schneider-Kreuznach Xenar 45mm f2.8 was one of the standard lenses that came with the Kodak Retina reflex cameras. Naturally, it has a DKL mount. Few years back, I bought a small box of DKL lenses from someone who said he used them as props. There are couple of the 45mm f2.8, three or four 85mm f4 and I believe one or two 90mm f4, all Schneider lenses. I used a few of them briefly with my 1D III with the EOS-DKL adapter, but though expensive, the adapter was very badly made, which makes using lenses on it a pain. Add to the fact that these lenses have pretty slow maximum aperture, which makes the optical viewfinder dark. Consequently, they didn't get much use.
Xenon 50mm f1.9 on left, Xenar 45mm f2.8 on the right. Note focus handle on the Xenar.
EVIL cameras change all that. The small aperture didn't affect much of the electronic viewfinder, except when the light is very dim, then the picture in viewfinder gets very grainy. In general use, EVIL cameras are perfect for these kind of lenses. I have already written about the Xenon 50mm f1.9 DKL, which I like a lot. This Xenar 45mm f2.8 is much smaller it can be considered a pancake lens, if not for the very thick adapter.
I think the biggest complain about this lens is the one meter minimum focus distance, similar to most rangefinder lenses of the same focal length. The fact that it has an f2.8 maximum aperture doesn't help if you try to shoot any close up pictures, or get shallow depth of field. No, this lens is not suitable for this purpose, but good as a general purpose lens. In fact, I am quite happy with it. It's a very sharp lens when stopping down a bit but the corner is note as good as that of the Xenon 59mm f1.9 wide open. The Xenar 45mm f2.8 is softer at the corners at f2.8.
Big Digger -- NEX-5N & Schneider-Kreuznach Xenar 45mm f2.8 DKL. Click for larger.
From f4 on, the lens is very good. It's a great walk around lens. Set the aperture to f5.6 or f8 and shoot. With the help of the EVF and peaking level, it's very easy to focus, though the focus travel is pretty short. For the low price, I think it's good value for the money, for a well made German lens. It's also very beautifully made and gorgeous to just look at and play with.
Man at work -- NEX-5N & Schneider-Kreuznach Xenar 45mm f2.8 DKL. Click for larger.