Jeff L writes:
Zeiss is bringing out a new high end line starting with the 55mm F1.4 distagon. The performance of this 135mm APO is so spectacular it makes me wonder why that lens is not part of the new line? It makes me think that they have even higher standards of performance in mind for the new lens line. I can't wait to see how it develops.
DIGLLOYD: The new Zeiss 55/1.4 Distagon is the first of a new ultra high performance line targeted at professionals with very high performance expectations, which in part means ultra low sample-to-sample variation (extremely tight build tolerances).
Extremely tight build tolerances tend to produce a high reject rate (non-saleable and/or rework required), and that means greatly increased costs. Hence a business decision must be made based on expected sales volume versus price. My guess is that the price of the 55/1.4 Distagon reflects anticipated challenges in building the design to the demanding tolerances that are required for all its optical magic to work—high performance requires high precision in every way.
The 55/1.4 Distagon is expected to be priced at an expected US $4500. My guess is that a large part of the cost accounts for an expected high reject rate, with the rest of the cost going to aspherics and special types of glass to deliver unprecedented performance in an f1.4 “normal” lens. Apparently Zeiss felt that the 135mm f/2 APO-Sonnar was more appropriately produced at a lower price point, which does not rule out a tight-spec variant in the future, but expect the cost to double.
It is also particularly difficult to produce perfectly symmetrical image rendition when the focusing helicoid is both moving and rotating the lens elements (as with all ZF.2/ZE lenses). The mechanical precision alone is extremely demanding on top of the required optical precision in grinding and assembly. Modern autofocus lenses typically only move a few small lens elements, yet even they have plenty of symmetry issues and significant variation in performance sample to sample.
As a current apropos example, the new Leica 50mm f/2 APO-Summicron-M ASPH remains extremely difficult to obtain; only a handful have reached the USA six months after the official shipping date (which was delayed 4-5 months, and I have no idea when I can get one). The delay and supply disappointments are almost certainly from difficulty in building them to tight tolerances: a very high reject/redo rate. And yet Leica builds these lenses by hand! It is very hard to design an ultra high performance lens and then actually build real lenses that meet specifications without an excessive reject rate.
In short: for a 36 megapixel or 56 megapixel DSLR, expect to pay 2X to 10X the price for lenses that perform to very high levels. Or to obtain multiple samples and test for a “best of 3/4/5”. Case in point: not long ago, I had three copies of the Canon 24-70/2.8L II, a very high performing zoom. All three showed significant variation; none were bad, it’s just that all of them were better here or there on the same scene (symmetry and alignment variation). I sent my own sample in and it came back as operating within specifications. And of course specifications are stipulated such that “pass or fail” makes almost all samples meet specification. Or the price goes up to account for a lot more “fail” samples.