Whites to White, Greys to Grey and Blacks to Black.

Almost every class we've had, our lectures have consisted of 50% other stuff and 50% Grey card business.
And at the end of almost every class i'm still asking the same question "Why do we need Grey Cards if we're using digital? Isn't that all programmed in?"
Wrong. Indeed it isnt.

In our exercise we had two readings we had to collect from two different backgrounds. The white background consisted of 1/30, ISO400 and f-29. The black background was 1/30, ISO400 and f-5.6. 
We set our meters to the centre weighted option.

In Deans immediate area the colour looks white but further out the colour turns to grey and it's pretty obvious. The colour temperture is set to tugensten and the f-stop is 16 to help reduce the overexposure that was 11.

By using a grey card correctly you can expell the grey look and keep the whites white, the greys grey and the blacks black.