Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3

[haring]

Have been using my Metabones Adaptor with the a7R III for Canon EF glasses.
However, I notice that with both the 50/1.2L and 85/1.2L II, both lenses only open up to f1.3, and not f1.2.
I am curious as to why that may be? Is it Metabones problem? Canon's? It obviously does not matter to the images, but I am curious why that may be the case. Anyone?


The lens is fully open but aperture is 1.3 not 1.2.... Anybody has the same problem?

[gstark]

I would not describe this as a "problem", but more of an expected outcome.

As soon as you introduce extra elements (or even just distance) into the optical path, you will most likely affect the optical performance, including your aperture.