You’ve learned an untruth. Welcome to the real world of 12% gray
lesenswerter Artikel bei bythom.com über Graukarten (18%, 12% oder 14%??) und die Belichtungsmessung.
Mit dem Fazit für den Digitalen Fotografen:
“If you shoot digitally, shoot a gray card under even lighting at the metered value, and at third-stop increments (use only spot or center-weighted metering, and make sure the card is angled slightly towards the light, as noted above). Look at the histograms for each exposure (on the camera, not in Photoshop, which uses a different method of generating histograms). If you’re using a gray card, pick the exposure setting that generates a centered value and set that in your exposure compensation control.”