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Lens Aperture cheating

I think many manufacturier are doing that but I had only the Fuji X-pro2 to test it:
Thanks to you library and the useful plugin for python I have computed gain of my detector using the photon transfert curve method, very simply.
I found of course that the gain increase with ISO as expected.
But also I checked something, the gain increase when you use a high aperture (in this case this is a 56mm f/1.2) on a lens which can communicate with the body.
Compare with the f/2.8 and above (don't know yet where the transition is) there is a factor 1.4 in the gain.
Measurement here :

This is due to the fact that at high aperture, the 'extra' light rays coming from the outer border of the pupil are hitting the pixel with a bigger angle. Pixel have a lower tolerance in angle, so what the manufacturers does is cheating the gain/ISO relation so the user is happy to see the expected extra stop of light which does not exists.

Well all this to illustrate the tricks of camera makers to be able to sell f/1.2 lenses (well you still get the bokeh) and the use of your library.