The Sunny 16 rule
The Sunny 16 rule is a way to meter for a correct exposure during the middle of the day without using your Nikon’s light meter. The basic idea is that, in daylight at an aperture of f/16, the correct exposure can be achieved with a reciprocal shutter speed to the ISO speed you’re using. For example, ISO200 would require 1/200 sec. As the conditions change, you simply alter the aperture. Use this table as a guide and try it out on your next shoot. Even the most sophisticated camera meters can be fooled in certain conditions, so this is a handy concept to keep at the back of your mind.