The Sunny 16 Rule

The Sunny 16 Rule is a relatively simple yet incredibly useful technique, used to achieve a correct exposure without taking a meter reading. It's a particularly handy trick for beginners- think of it as a cheat sheet - a way to read the light and learn which settings you need for a good exposure.

Photo by @alex.frayne

Everything you need to remember about the Sunny 16 rule is in the name - if it's a sunny day with no clouds, and your aperture is at f/16, your shutter speed will be the same as the ISO value. So, if your ISO is 200, at f/16 your shutter speed will be 1/200, and if your ISO is 400, at f/16 it will be 1/400. This relationship between ISO and shutter speed will ensure you get the same well-exposed photos each time, assuming you remain in the sun.

That's the basic premise of the Sunny 16 rule. However, it can also be used to determine the shutter speed settings at other aperture values, and adapted based on the light and weather conditions.

Photo by @levihemphill

If you remember from our previous post, exposure is a balancing act between ISO, aperture and shutter speed. As the aperture is changed, the shutter speed will move in the opposite direction to counteract that. Sunny 16 acts as the starting point for working out this balance. The number of stops you change the aperture from f/16, is the number of stops in the opposite direction you need to change the shutter speed. Look to the table below as an example of how this would work with an ISO 200 film.

So, by judging the light conditions you can use Sunny 16 to achieve well exposed photos without the use of light meter. Here's a list of weather conditions, and the corresponding aperture settings they require. 

• Sunny, with clear, bright skies - f/16
• Sunny with light clouds - f/11
• Mostly cloudy, but not fully overcast - f/8
• Overcast or in outside shade (for example, under an awning on a sunny day) - f/5.6
• Complete shade, or as the sun is going down - f/4

Photo by @shotnotfromthestreet

I find it helps to give an example of how you would work out exposure using Sunny 16- so, let's imagine it's a slightly overcast day, and you are shooting on ISO 200 film. Firstly, because of the light conditions, you would set your aperture to f/8. Now, because your aperture has been pushed two stops (from f/16), you have to move your shutter speed down two stops to counteract this. You're moving it down two stops from 1/200, because you're shooting with ISO 200 film. So, using the Sunny 16 rule, your exposure settings would be, f/8 for 1/800 seconds.

Finally, the Sunny 16 rule is a good way to check your camera's exposure tendencies. Some cameras tend to slightly under expose, so this is a good way to check whether this is the case.

The Sunny 16 rule is a useful and easy way to get to grips with correct exposure, and it means you don't have to keep stopping to use a light meter when you're out shooting. It does only work when you're outside, in the sun, but it's such a great technique and skill to have in your toolkit, especially as a beginner photographer. 

Photo by @adamwilkoszarski

Cover photo by @taylordorrell

Author: Becca Knight