Zeiss ZM 50mm f1.5 C-Sonnar: Portrait of a lens

Sigfrid Lundberg's Stuff 2012-11-18

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The 50mm Sonnar f1.5 is a transplant from the Zeiss Contax rangefinder world. A real classic there. Also, it is indeed a personality with a focus shift, which isn't a bug but a feature.

There are a number of people who have reviewed this lens. Some of them have really strong opinions.

L1000031_v1 by Sigfrid Lundberg, on Flickr

Figure 1. A study in depth of field of the Sonnar 50mm Sonnar lens. It is shot with my Leica M-E, so it is possible to focus this lens with a M-mount rangefinder.

The engineering behind this lens is so well described in the LaVidaLeica review:

When it comes to performance, the Sonnar is almost like having two distinct lenses. Wide open at f/1.5, the lens is well-known for the "Sonnar look." Very hard to define, but one you'll know when you see it. The bokeh is unique and the rapid transition from in- to out-of-focus regions makes the depth of field appear thinner than you might expect. Some unfairly call the lens "soft" wide open, but that's not entirely true. The central region is sharp and well defined, but due to curvature of field - the corners and edges soften up from the center. This makes for dramatic separation of your subject from the background. As you stop down, especially from f/2.8-4 and down - the lens sharpens up across the field quite rapidly and approaches the level of modern lenses. This is the behavior that fans of this lens really enjoy.

Nick Devlin says

Unfortunately, in over a hundred frames I could only produce one sharp(ish) frame at f1.5. Fearing user-error, I went to the extreme of fixing my M8 on a tripod in broad daylight, focusing the lens with the absolute maximum precision I could muster on a subject 10’ away, and firing comparison frames on the self-timer. The results were still mushy.

I like my Sonnar. Indeed I love it. I've used it more than any other since I acquired it. So my conclusions is close to LaVidaLeica. I've got two very good lenses, with very different qualities. And I claim that I can predictably get very sharp images with the lens wide open. (Figure 1).

Below you find images taken with the aperture open or even wide open. You'll see the Sonnar bokeh, but there are also shots taken with the lens stopped down to aperture 5.6 or 8 or even 11. That is street or landscape photography, where there is need for the background to be an integrated part of the composition.

R0011816.JPG by Sigfrid Lundberg, on Flickr
R0013804.JPG by Sigfrid Lundberg, on Flickr
R0013381.tif by Sigfrid Lundberg, on Flickr
R0014554.JPG by Sigfrid Lundberg, on Flickr
R0012542.tif by Sigfrid Lundberg, on Flickr
R0012078_v2 by Sigfrid Lundberg, on Flickr
R0013332.tif by Sigfrid Lundberg, on Flickr
L1000190_v1 by Sigfrid Lundberg, on Flickr


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My name is Sigfrid Lundberg. The stuff I publish here may, or may not, be of interest for anyone else.

On this site there is material on photography, music, literature and other stuff I enjoy in life. However, most of it is related to my profession as an Internet programmer and software developer within the area of digital libraries. I have been that at the Royal Danish Library, Copenhagen (Denmark) and, before that, Lund university library (Sweden).

The content here does not reflect the views of my employers. They are now all past employers, since I retired 1 May 2023.

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