This was posted by Nick Miners. It’s a very clear and concise explanation of what the Zone System for exposure calculation is, and how to do it.
The Zone System is something I’ve looked at for a while, but never clearly got my brain around what it achieves over existing exposure methods I can do with my camera. Nick has very adequately covered the why and the wherefore, although I’m discovering with my poor old stunted EOS 400D, it’s not actually capable of spot metering in the accepted sense.
So, I have to consider alternative methods, such as an 18% grey card and all other kinds of paraphernalia. I think getting properly into the Zone is going to have to wait until I get a better camera!