sunny 16

Cumulus Clouds 

1/200 sec @ f/16, ISO 200, Nikon D700, 28mm

When I was 14, my best friend's dad taught us how to use the camera. I don't remember exactly, but from what I recall, he told us to set the aperture to f/11 or f/16 on a sunny day, f/8 on a hazy day, f/5.6 on a cloudy day, and f/4 when it's foggy. I really never asked why.

Then somewhere along the way I read about the "Sunny-16" rule of thumb for exposure, which goes something like this...

      On a sunny day, set your f/stop to 16, and shutter speed to the inverse of your ISO.

For example, if the ISO is set to 200, set your shutter speed to 1/200s, and aperture to f/16. That would produce a good ball-park exposure. And in film (well, negative film anyway) days, ball-park was good enough.

And leaving the ISO and shutter speed where they are, on a hazy day you'd open up a little bit to f/8 to let in more light. Still more on a cloudy day to f/5.6. And so on. Kinda makes sense huh.

Try this: on sunny day, set your camera's aperture to f/16, and point the camera to the blue sky, and see if it suggests a shutter speed that's (roughly) the same number as your ISO setting. Worked for the clouds pic above!