FrankS
Registered User
Hey, Taffy. The ground could be ashalt, grass, dirt, or concrete. Concrete would be a bit lighter than 18% grey, just like your palm is a bit lighter than 18% grey. Open up a stop from your palm or from light coloured concrete. The bright blue sky (with no sun) is 18% refectance too, but then if you're seeing bright blue sky, that's simply sunny-16.