Substitute metering and ethnic background.
From How To Select and Use Nikon & Nikkormat SLR Cameras, Chapter 8: Exposure Metering --
A very handy substitute metering surface is the palm of your hand. You should check your own palm but light skin typically reflects about one step more light than an 18% gray card. If so, you can hold your palm in front of the camera--in the same light as the subject or scene--meter on your palm and then open up one step. If your palm reflects only half a step more, obviously that's how much to open before shooting.
"If your palm reflects only half a step more" = if you're not white? Well, my palms are pretty light I think so I'd say they're one step more than an 18% gray card. And palms in general are the lightest part of the skin aside from the soles of your feet, right? So I guess you could meter with the soles of your feet too. Unless you've been walking around barefoot all day and your feet are dingy.
A very handy substitute metering surface is the palm of your hand. You should check your own palm but light skin typically reflects about one step more light than an 18% gray card. If so, you can hold your palm in front of the camera--in the same light as the subject or scene--meter on your palm and then open up one step. If your palm reflects only half a step more, obviously that's how much to open before shooting.
"If your palm reflects only half a step more" = if you're not white? Well, my palms are pretty light I think so I'd say they're one step more than an 18% gray card. And palms in general are the lightest part of the skin aside from the soles of your feet, right? So I guess you could meter with the soles of your feet too. Unless you've been walking around barefoot all day and your feet are dingy.