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Author Topic: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3  (Read 889 times)

haring

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

E.J. Peiker

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Re: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
« Reply #1 on: May 05, 2018, 06:16:27 AM »

Sounds like a firmware issue on the Metabones.
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BartvanderWolf

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Re: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
« Reply #2 on: May 05, 2018, 11:44:36 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

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== If you do what you did, you'll get what you got. ==

haring

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Re: Sony A7r III with Canon 1.2 lenses - Aperture error - 1.3
« Reply #3 on: May 05, 2018, 12:25:08 PM »

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! :)
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