However, a critical part of the 21mm's quality was due to coatings that used lead - this manufacturing process is now outlawed in Europe under the ROHS Directive (the same law that caused Hasselblad to abandon one of its most popular models, though in that case it was lead solder).
If using different coatings Zeiss can still match the quality of the C/Y lens, that would be very good news indeed.
Being a user of lenses I am no expert in the field of coatings.
I have many C-Y lenses including 21mm 2.8. Nobody will question its performance. It is a lens with th highest number of elements when you compare it to other brands. Coatings play a big role in its performance.
I have other Zeiss lenses of the next generation. They are the smaller ZM ones. I feel they are very good with respect to their coatings. ZM15 2.8 has many elements as well, it is very contrasty and flare resistant with both properties being related to the excellent performance of the coatings.
I would believe,despite the abandonment of lead in manufacturing process, Zeiss maintains its standard in coatings.
I wouldn't agree. Despite its excellent reputation for people using small format digital SLR, making C-Y 21 2.8 is well within Zeiss capability. Zeiss is a ginormous lens maker, she is making lenses logarithmically more complicated than CY21 2.8.
Despite the high market demand, she is not making it now only because she is working very slowly in the photographic department. Photographic lens production occupies only a tiny portion of this company.
For those who is interested in the lens design and MTF of the new ZF/ZK 2/28, you could email email@example.com.
This new lens is similar to C-Y 2/28 that it can focus down to 0.24mm. Close focusing capability together with f2 at 28mm suggested they are very good lenses. The new ZF/ZK 2/28 outperform C-Y 2/2.8 in all f-stops. For instance, ZF at f2 is better than C-Y at f2, ZF at f4 is better than C-Y at f5.6.
In view that the ZF/ZK in general are better than their C-Y counterparts, I am pretty sure that when they come to the new ZF/ZK 21 2.8, it will outperform C-Y 21 2.8. It is breathtaking, isn't it ?