In article , afn09444@afn.org says...
>On 3 Jan 1997, Bob Neuman wrote:

>> First, why did you choose the Northern sky as a reference?

> He probably saw it in the same book I did...THE WORLD'S SIMPLEST
>PHOTOGRAPHY BOOK, by Jerry Hughes. I just checked it out from the library.
>Trying to learn the basics myself, as well. :)

Ah, I would not recommend using anything that is primarily blue as a
reference for calibrating exposure meters - it is one of the colors
that exposure meters read innacurately, and differently, depending on
meter type... Grey, or a mix of tones/colors, under standard lighting
conditions would be more reliable.
Hope This Helps