Zeiss ZF 28mm f/2 Distagon announced

2007-09-17 • SEND FEEDBACK |
Related: distortion, optics, vignetting, Zeiss, Zeiss 28mm, Zeiss 28mm f/2 Distagon, Zeiss Distagon, Zeiss DSLR Lenses, Zeiss Lenses

Zeiss today announced the 28mm f/2 Distagon [images], to be available by the end of 2007 for US$984. It’s a lens that is very interesting to me, especially if it can perform as well as the 35mm f/2 Distagon (see previous comments). If you’ve been reading this blog, you’ll know that I’m very impressed with several of the Zeiss ZF lenses, a feeling shared by several readers of this blog who emailed me. I’m well along on my review of the Zeiss ZF lens line, and so the 28mm won’t be included in the first version. It’s about a lot more than sharpness, and I’ll be speaking to that in my review.

  
Zeiss 28mm f/2 Distagon (images courtesy of Zeiss)

In typical Zeiss fashion, the tantalizing description from the German press release (in English) includes such gems as “outstanding properties”, “ideally suited”, and “the performance potential of the lens is also available throughout the entire image field even with professional digital cameras featuring full format sensors”. Please don’t read the latter unless you’re fully sober—it might put your brain into overload.

And did you know that f/2 is “ideally suited for taking pictures in unfavorable lighting conditions” or that “28 mm lenses are primarily used for landscapes...”—surely Zeiss doesn’t really believe that its customers need that explained. And it’s rather silly, since the sensor size could vary wildly between cameras (and hence the field of view). To me, “unfavorable lighting” means strong backlighting or flat light, not necessarily low intensity, hence I just can’t “stay with the crowd” on that one.

There are a few specific details of the 28mm (28.5mm) Distagon. Unlike the ZF 25mm (25.7mm) f/2.8 Distagon, “floating” elements are used. This is really important to make the 28mm perform well at both near and far distances, a limitation of the 25mm f/2.8 Distagon whose strong curvature of field can be exploited, but is not usually desirable. The 28mm Distagon also allows near-macro reproduction ratios (1:5) a feature which extends its versatility.

Zeiss ZF 28mm f/2 Distagon schematic

I just can’t see owning a 25.7mm and a 28.5m lens—2.8mm is significant, but still much too close to justify buying and carrying both. The floating elements and f/2 aperture of the 28mm make it a really easy decision in favor of the 28mm. Zeiss needs a 24.0mm lens to replace the 25mm Distagon. A 24.0mm f/2 would do nicely, along with a 20mm f/2 and a 16mm f/2.8.

The technical specifications including MTF, distortion and vignetting suggest a generous dollop of Zeiss optical magic, as well it should, at US$984. The MTF (measured not computed) looks particularly impressive, keeping in mind that the lines are at 10, 20 and 40 line pairs/mm. (Canon’s charts top out at 30 line pairs/mm). Note also that on less than full-frame cameras (such as the EOS 1D Mark III [buy one @AMAZON]), MTF is stellar across the frame. On full-frame cameras, the extreme corners are going to go a little soft, though not necessarily worse than any other 28mm lens.

MTF of Zeiss ZF 28mm f/2 Distagon at 10, 20, 40 line pairs/mm
MTF of about 50% across most of the field at 40 line pairs/mm @ f/2 is outstanding

Distortion and vignetting are typical of the Zeiss Distagon designs, with distortion being nicely linear across the frame, more easily accepted by the eye than the “moustache” distortion seen with some wide angle zoom designs.

MTF—measured vs computed: some manufacturers publish MTF charts based on computed MTF eg the MTF achieved by the lens design assuming perfect manufacturing and assembly—something unlikely to occur with most samples. As far as the author knows, Canon, Nikon, Sigma, etc all publish computed MTF. By comparison, Zeiss publishes MTF that is measured from a real lens, and all lenses must meet that minimum performance level or they are not shipped to customers. Furthermore, MTF at 40 line pairs/mm is a much more demanding standard than at 30 line pairs/mm. Also, the spectral weighting influences the results. The upshot is that MTF of Zeiss lenses can’t be directly compared against other most other brands.