21mm Biogon - ZM - Thoughts?

[Mark J]

Thanks Henning and 'Warden' for further info. I can only assume that Zeiss have changed their policy regarding 'nominal' vs. toleranced MTF on the 2000's. If this is the case, then so be it. It is somewhat surprising because it would put Zeiss at a 5 to 10% disadvantage with respect to any other manufacturer, when comparing MTF curves. I don't remember any 'adjustment' being discussed or made to the MTF when we created the datasheet for the 300/2.8, the curves looked exactly as they came out of the computer design.

 

[Henning Serger]

Thanks Henning and 'Warden' for further info. I can only assume that Zeiss have changed their policy regarding 'nominal' vs. toleranced MTF on the 2000's.

Mark, it could be that their decision to publish real test data of produced lenses has to do with the development of the new Zeiss K8 MTF metering unit. AFAIK it has been introduced around 2000/2001. In my talks with the Zeiss staff I had the impression that they were quite proud of the excellent capabilities and performance of the new K8 system.
And just a bit later in 2004 another great step and change for Zeiss with the introduction of the Zeiss Ikon ZM and the new ZM lenses.
And in 2006 the introduction of the new SLR lens line with the ZE, ZF and ZK lenses.
Both were very surprising (in a positive way) steps for the market. And the policy of publishing real test data perfectly fit to these two new product lines at that time.

If this is the case, then so be it. It is somewhat surprising because it would put Zeiss at a 5 to 10% disadvantage with respect to any other manufacturer, when comparing MTF curves.

That is right. The real test data is the much more honest and realistic data. And at first sight it indeed put Zeiss at a disadvantage, at least for the uninformed customer. But the informed customer who has read that Zeiss is using real test data will most probably really appreciate that.
And in my talks with Zeiss I always had the impression that Zeiss made that decision very consciously / deliberately. Because they think it is much more honest and much better information for the customer.

Best regards,
Henning