So, just find a 18% gray object and spot meter that. The bark of trees can work. Even the green in trees maps to grey for most trees. Sometimes you can even use a blue sky with the right shade.Originally Posted by Leon
With a spot meter, I think its easier--just find something that is gray and meter it. Take a few meters of different grays and then average them. Works the same as the other three methods.
Or, I just realized, bring a small gray card, put it in the same light as the subject and spot meter off that!