A Few Issues Need Your Suggestion

Started 2 months ago | Discussions thread
MOD Tom Caldwell Forum Pro • Posts: 38,771
Does Metabones trickery overcome Viltrox plain thought?

Heritage Cameras wrote:

Ching-Kuang Shene wrote:

I acquired a SIgma AF 1000mm 1:8 APO in Canon EF mount. So, I tried to put it on Sigma MC11 so that I could use this combo on my Sony A7II. However, I found that the lens transmitted f/5.6 (rather than f/8) to A7II via MC11.

Some slow independent lenses deliberately report an incorrect maximum aperture, in order to trick cameras that can't AF below f/5.6 into working (not always very successfully). I've seen this in zooms before, so this may be by design.


This is an interesting point in another quite obscure way when electronic focal reduction adapters from EF mount are used

Viltrox adapters (officially - from “the horses mouth”) will not work with EF lenses f1.2 or faster.  They show the increased light in their effective aperture reproduction on camera body but also “dark screen” and lock up.  On the other hand “f1.2?” Says Metabones, “No trouble”.  They work fine - but for some reason do not update the stop information on the camera body read-out - as is the practice with all other slower lenses.

ie: the standard scales are what the camera body acknowledges - “set f1.2” still registers as “f1.2” and the same happens for every setting.

Maybe Metabones is also using a similar aperture (mis-)reporting system to trick the faster lenses into working? - or has the meticulous Metabones firmware simply overlooked this one particular faster lens situation?

I did absent-mindedly think that perhaps the Metabones Ultra wasn’t even focal reducing - but this is impossible as the glass elements are in there doing something ... I did think that maybe “f0.9 or whatever” might not be capable of being shown via the camera electronics - but Viltrox manages to show this but nothing much else.  I have also tried the full range of settings with the Metabones adapter -  f1.2 through to f16.0 and the camera body mimics the actual mechanically set aperture.

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Tom Caldwell

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