why exposing with 18% gray card does not give IRE near 40 I am trying to understand how to get perfect exposure using gray card.
With my Sony a6500 using ITU709 gamma, I locked exposure by doing spot metering on the gray card.
When importing in final cut pro the waveform monitor show IRE value near 25 for the gray card.
Shouldn't it show between 40 and 43 for 18% reflectance mid gray?
I was stupid and using spot focusing and not spot metering.
So the metering was wrong even if the focus was right in the middle of the card.

I repeated the test and it now give me 40 IRE as expected.