Have you ever wondered if you meter is giving you the right exposure? Do you ever wonder how to figure out the proper exposure yourself? Well it is possible—with the f/16 rule.
The theory is simple. The basic exposure for a camera on a bright sunny day will be f/16 when the shutter speed matches the ISO. That is it … seriously!
If you have a great sunny day, set your ISO to 200 then set your shutter speed to 1/200 sec. The f/stop should be f/16. If you change the ISO then change the shutter speed accordingly. If weather conditions change, then you change the f/stop.
f/22- reflective sand or snow
f/16- bright sunny day
f/11- bright cloudy day
f/8- slightly overcast
f/5.6- heavy overcast or open shade
Now, this is to get a base exposure to work from. After you have your basic exposure you can make adjustments to fit the photograph you are creating.
In situations where you find that you are shooting with the sun on the back of your subject and their face in the shade (and assuming you are shooting a face on portrait), just make an adjustment by opening up two f/stops. So if the base exposure in the f/16 rule tells you that you should be shooting f/11, then open up two f/stops to f/5.6.
Even if you have a great light meter, there is some comfort in having the skills to know that your meter is in the right ball park. When you can work it out in your head, the chances between success and failure of a photograph is significantly reduced.