The January 2005 Asahi Camera compares the new Cosina-manufactured 25/28/35/50mm Zeiss-Ikon lenses against their Leica contemporary equivalents (ASPH when possible). In the shootout, which I was reading while browsing through a bookstore, the ZI lenses come out as equivalent in flare tolerance (both the ZIs and ASPHs were basically flare free); the ZIs were basically the same in sharpness and color temperature (although the ZIs were a tad warmer); and I think the 50 Planar was just a tad less contrasty which the reviewer thought gave better shadow depth.
25/2.8 Biogon T* vs. 24/2.8 Elmarit ASPH
28/2.8 Biogon T* vs. 28/2.8 Elmarit
35/2 Biogon T* vs 35/2 Summicron ASPH
50/2 Planar vs the 50/2 Summicron
Note that all of the ZI lenses are estimated to be selling in the $800-900 range (Y80,000-90,000 street in Japan). While this makes the 50mm Planar only so-so against the 50mm Summicron, the wides are much cheaper than the Leica equivs. I have the 28/2.8 and 35/2 on hold myself. I think it'll come out in January, production has been delayed for some reason (they were originally going to come out in November).
The ZI lenses are testing at the same level as the Leica lenses but at one third the price. And the reviewers are using them in conditions that even famed photojournalist Ted Grant would approve -- shooting from the shadow side in heavily backlit portrait situations. They do say that even the highest end zooms would flare out in these situations but the ZI and Leica ASPH do wonderfully.
They do mention bokeh and OOF. They say they are roughly equivalent but the ZI is softer while the ASPH generally are a bit harsher and thicker. These were all subjective tests using real photgraphs and real models, by the way. Not MTF or lab tests. And contrary to what you might say, you can tell the difference even in a magazine reproduction. All the lenses were tested wide open. Stopped down, the reviewers say the difference disappears.
All in all, I'm really excited by this news. If you're not interested, then don't buy or read! :-)
