[Leica] Zeiss Ikon Focus Shift

[billgem at hotmail.com (Bill Marshall)]

Alex Hurst wrote:
>"FWIW, this would seem to be a variation on the Nikon CRC system which 
>optimizes focus in close."

You may be on to something, Alex, because the 85/2 ZM Sonnar does employ 
floating elements, which is exactly what Nikon's CRC design does. In the CRC 
(close range correction) system, these 'floating" elements move within the 
lens as the focus distance changes. The ZM 85/2.8 also "incorporates an 
ultra-precise, nonlinear RF coupling mechanism" paired with the floating 
element design. Nikon uses its CRC system not only with medium telephoto 
lenses but also with extreme wide  angle lenses, where such focus problems & 
resultant image deterioration also occur. Sure enough, the new 15/2.8 ZM 
Distagon employs a floating element design as well. These are the 2 new 
Zeiss lenses that will be manufactured directly by Zeiss in Germany & have 
not been subcontracted to Cosina because of their lack of experience & 
equipment necessary for this type of lens manufacture.

I wonder if they are also using something similar or equivalent to Nikon's 
ED glass, which they employ especially on their ultra-wide angle optics. 
Zeiss too stresses in its literature the use of "exotic optical materials"* 
in the manufacure of the 15/2.8. It's interesting to note as well that Nikon 
lenses using ED glass also employ special focusing mechanics to accomodate 
"a shift in the focus point" (from "The Nikon Compendium"). For Nikon, too, 
these are among their most expensive lenses "due to the unusually high 
manufacturing costs involved in the production of ED lenses."

Funny thing is that no one called it "hype" when Nikon introduced the CRC 
system. What is the resistance to this new Zeiss product line that prompts 
such comments?