Sunny 16 Rule
The Sunny 16 Rule is probably one of the most important “rules” to know in photography. There’s lots of “rules” to learn, some of which can be ignored, but knowing and understanding the Sunny 16 Rule will help you make better photographs quicker when shooting in Manual Mode. It might even save your bacon one day! Anyone ever had their light meter stop working? I have… Sunny 16 to the rescue!
So, how does knowing the Sunny 16 Rule help you? Especially if your light meter stops working… It’s because you learn to get the correct exposure without actually having to use a light meter!
Understanding the Sunny 16 Rule alone can help you make better photographs without needing to rely on the automatic modes of your camera. It’s one of the first steps to moving out of Auto Mode into Manual Mode and taking control of both your camera and your images. It’s a great rule of thumb when it comes to getting the exposure right. It might not be perfect, but it’ll be very close… every single time.
The Sunny 16 Rule is simply this –
On a bright sunny day, you set your camera’s aperture to f16 and the shutter speed to the reciprocal of your film speed or ISO.
Really simple isn’t it?
Using the Sunny 16 Rule
So, let’s take a look at how the Sunny 16 Rule works in real life.
If your camera’s ISO was set to 100, you would set your camera’s aperture to f16 and the shutter speed to 1/100 second. “But my camera doesn’t have 1/100 second as a shutter speed” I hear you say. Not a problem. Remember, this rule is a guide… a great guide at that, but it’s still a guide. Your exposure will be very, very close to correct if you’re somewhere close to the ideal setting of ƒ16 and 1/ISO.
Many cameras no longer have 1/100 second as a shutter speed selection, so instead you would use 1/125 second because that’s the closest to 1/100. Similarly, if the camera’s ISO was set to 200, you would change your shutter speed to 1/200 second (or 1/250) and if the ISO was changed to 400 you would change your shutter speed to 1/400 second (or 1/500 if your camera doesn’t have a setting of 1/400). As you can see, the science of this rule isn’t exact, but it’s certainly very workable and will get you close every time you use it.
It’s a pretty simple rule to understand and it’s definitely a good one to know. It gives you a great starting point if you want to shoot in Manual Mode. After a while, you’ll start to see the intensity of the light better and you’ll make adjustments accordingly.
What if it’s not sunny?
We all know that it’s not sunny all the time, so, what do you do if it’s overcast or raining? You simply adjust your settings based on your knowledge of this rule. Remember, practice makes perfect and the more you look at your surrounding light and think about how it compares to “sunny”, the better you’ll get at making adjustments.
Maybe it’s a little overcast, so you might change your shutter speed from 1/200 (1/250) to 1/100 (1/125) for ISO200. It’s really not an exact science, but knowing this rule will always get you close. It’s definitely a good place to start without having to think too hard about the exposure. If the light is darker, then you need to increase the amount of time your shutter is open, or make the aperture larger to let more light through. It doesn’t matter which setting you change, so long as you increase the amount of light hitting the sensor. Of course, you could also increase the ISO, which would have the same effect.
Here’s a handy table taken from Wikipedia that shows some of the variations you might use with the Sunny 16 Rule. In these examples you would still set your shutter speed to the reciprocal of your ISO (1/100 or 1/125 for ISO100; 1/200 or 1/250 for ISO200; and so on).
|Aperture||Lighting Conditions||Shadow Detail|
|f22||Snow / Sand||Dark with sharp edges|
|f11||Slightly Overcast||Soft around the edges|
|f5.6||Heavy Overcast||No shadows|
|f4||Open shade / sunset||No shadows|
No need to use ƒ16 all the time
Exposure has three components… shutter speed, aperture and ISO. It really doesn’t matter how you change each of those settings, provided the overall base exposure remains the same. You could, for example, make the aperture larger to let more light in and then make the shutter faster to reduce the light again to bring the exposure back to what it was before you increased the aperture. That means you don’t need to use f16 every time you make a photograph. If you opened the aperture up by four stops from ƒ16 to ƒ4 (ƒ16 → ƒ11 → ƒ8 → ƒ5.6 → ƒ4) you could simply adjust your shutter speed by four stops to compensate.
Real world example
If it’s a nice sunny day and you’re shooting with an ISO of 200, then Sunny 16 states your exposure should be 1/200 second at f16. You’ll make that 1/250 second to match the available settings on your camera. Taking that information into consideration you can change the settings to achieve your artistic goals.
If you want a shallow depth of field to isolate your subject against a soft out of focus background, you could:
- Reduce ISO200 to ISO100 – By reducing ISO200 to ISO100 you’ve reduced the light entering the camera by one full stop. That means to keep the same exposure you need to change the aperture or shutter speed (or a combination of both) to add one full stop of light back into the image;
- Open the aperture up from f16 to f11 – you’ve now added one full stop of light back into the image and slightly reduced the depth of field. You still want to reduce the depth of field even more though; so
- Open the aperture up from f11 to f2.8 – you’ve now added four full stops of light back into the image. In other words, the image is going to be over-exposed by four stops. You need to reduce the overall exposure again by changing the shutter speed;
- Change the shutter speed from 1/250 second to 1/4000 second – you’ve now reduced the amount of light entering the camera by four full stops, which brings the exposure back to the equivalent of your original exposure of 1/250 at f16.
As you can see from the example above, a shutter speed of 1/4000 second combined with an aperture of ƒ2.8 and an ISO of 100, is the exact same exposure as 1/250 second at ƒ16 and ISO200. You’ve still applied the Sunny 16 Rule to the scene, but you’ve adjusted it fit your artistic wishes.
Combining the Sunny 16 Rule with your knowledge of the Exposure Triangle will enable you to pick a starting point based on the ambient lighting conditions and your artistic intent and be close to a perfect exposure every time.
Time to go practice!
Start looking around you at the light and working out how it relates to “sunny”. Have a go at guessing what settings you would use and then actually raise your camera and see what settings the camera calculates. The more you practice, the more accurate your “guesses” will become.
Above all else, have fun!