p.1 #2 · Carl Zeiss Biogon vs Sonnar - what's the difference (?)
Here is a bit of history about Zeiss lens design designations. Biogon and Sonnar represent different types of design. Zeiss also has a description somewhere but I can't find it right now, so this will have to do: http://www.panix.com/~zone/photo/czlens.htm
There are performance/IQ/application differences inherent in the different designs. On the RX-1 a Biogon design might not have been feasible (sensors are picky about oblique light angles hitting it) and a Sonnar-type design probably allowed for a more telecentric design among other requirements and characterisitics.
p.1 #4 · Carl Zeiss Biogon vs Sonnar - what's the difference (?)
Quote:
Sonnar-type design probably allowed for a more telecentric design.....
Un-quote
Suppose that is because of the full frame sensor (?)
I will thank you both for the link to the Carl Zeiss pages with the explanation about the different designs of their lenses (Biogon, Sonnar, distagon, etc...).
p.1 #6 · Carl Zeiss Biogon vs Sonnar - what's the difference (?)
The Biogon is a symmetric lens design (though, so is the Planar; the Biogon's halves are more complicated), and the chief feature is that it can produce a wide-angle lens with very low geometric image distortion.
Zeiss categorizes lenses in these families by the overall design; often, they are not really that pure. For instance, the 2/35 ZM is not really a symmetric design. They may have used that as a starting point, but then they added various corrections to end up with the qualities they desired (perhaps less CA, perhaps it was necessary to get an f/2 aperture, etc). It is very sharp when stopped down, and has essentially zero geometric distortion.
