Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: haring on May 04, 2018, 06:49:57 pm

Title: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
Post by: haring on May 04, 2018, 06:49:57 pm

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?

Title: Re: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
Post by: E.J. Peiker on May 05, 2018, 06:16:27 am

Sounds like a firmware issue on the Metabones.

Title: Re: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
Post by: Bart_van_der_Wolf on May 05, 2018, 11:44:36 am

Quote from: E.J. Peiker on May 05, 2018, 06:16:27 am

Sounds like a firmware issue on the Metabones.

Could be, and maybe only in the EXIF. The nominal f/1.2 is mathematically f/1.259921 (from 2^(1/3)), therefore rounded to f/1.3 ?

Not sure if one can see any difference between f/1.3 and f1.2 when looking through the lens from the front (entrance pupil).

Cheers,
Bart

Title: Re: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
Post by: haring on May 05, 2018, 12:25:08 pm

Quote from: BartvanderWolf on May 05, 2018, 11:44:36 am

Could be, and maybe only in the EXIF. The nominal f/1.2 is mathematically f/1.259921 (from 2^(1/3)), therefore rounded to f/1.3 ?

Not sure if one can see any difference between f/1.3 and f1.2 when looking through the lens from the front (entrance pupil).

Cheers,
Bart

Yes, this is it! I It is rounded up! :)