The short version
- Bright sun: f/16, shutter speed at 1 over ISO.
- The shutter speed is the reciprocal of the ISO: ISO 100 gives 1/125, ISO 200 gives 1/250, ISO 400 gives 1/500.
- Worse light means opening the aperture: f/11 for haze, f/8 for bright overcast, f/5.6 for heavy overcast, f/4 for open shade.
- It works because midday sunlight is remarkably consistent, about EV 15.
- Use it on meterless film cameras, as a sanity check on digital, or to preset exposure before raising the camera.
Sunny 16, exactly
On a clear sunny day, in the middle of the day, with the sun on your subject, set the aperture to f/16 and the shutter speed to the reciprocal of your ISO. That is the whole rule. Here it is worked out for the common ISOs:
| ISO | Shutter speed | Aperture |
|---|---|---|
| 100 | 1/125 | f/16 |
| 200 | 1/250 | f/16 |
| 400 | 1/500 | f/16 |
| 800 | 1/1000 | f/16 |
Cameras do not have 1/100 or 1/400 on the dial, so you round to the nearest click. 1/125 stands in for 1/100 and nobody can tell the difference.
The Sunny 16 variations for every light
Sunlight is not always full blast. The classic variations keep the shutter speed at 1 over ISO and open the aperture as the light drops, one stop per step:
| Light | Aperture | Example |
|---|---|---|
| Bright sun, hard shadows | f/16 | Midday beach |
| Slight haze, soft shadows | f/11 | Thin high cloud |
| Cloudy bright, no shadows | f/8 | Overcast but bright |
| Heavy overcast | f/5.6 | Gray sky, dim day |
| Open shade, sunset | f/4 | Under a tree, golden hour fading |
One exception: bright snow or white sand reflects so much light that you stop down instead of opening up. Think of it as Sunny 22.
Why the rule is true
Bright midday sunlight measures about EV 15 almost everywhere on Earth, on any clear day. That is the key insight: the sun is a constant. f/16 at 1 over ISO is simply the exposure that matches EV 15, dressed up as a memory trick.
This is also why the rule belongs with the exposure triangle. Sunny 16 is one correct exposure, and the triangle shows you every equivalent way to get it. f/16 at 1/125, f/11 at 1/250, f/8 at 1/500, f/5.6 at 1/1000, and f/4 at 1/2000 are all the same amount of light at ISO 100. The rule hands you the starting point. The triangle hands you the options.
When Sunny 16 earns its keep
- Film cameras with no meter. This is what the rule was born for. Many classic cameras never had a meter at all.
- Dead battery. A mechanical film camera keeps working with no power. Sunny 16 keeps you shooting.
- Sanity check on digital. In bright sun, if your meter suggests something far from f/16 at 1 over ISO, check your settings before you trust it. Meters get fooled by bright skies and dark subjects.
- Street photography. Preset f/8 or f/11 at 1/500 on a sunny day and shoot without chimping. The exposure is already right when the moment happens.
Common Sunny 16 mistakes
- Forgetting the shutter follows the ISO. The rule is two settings, not one. f/16 at 1/60 with ISO 100 is two stops overexposed.
- Using it at the wrong hour. It assumes midday sun. At 7 PM the light is several stops dimmer and the rule will underexpose.
- Backlit subjects. The rule exposes for frontlit scenes. A subject against a bright sky needs extra light, usually one to two stops more.
- Snow and sand. All that reflected light fools the rule the other way. Stop down to f/22 instead of opening up.
Get the printable camera settings cheat sheet
Two pages for your camera bag: starter settings for portraits, landscapes, sports and night shots, the handheld shutter speed rule, and the five settings rules worth memorizing, including Sunny 16.
Frequently asked questions
What is the Sunny 16 rule in simple terms?
In bright midday sun, set your aperture to f/16 and your shutter speed to 1 over your ISO. At ISO 100 that is 1/125 at f/16; at ISO 400 it is 1/500 at f/16.
What shutter speed do I use with the Sunny 16 rule at ISO 200?
1/250 at f/16. Match the shutter speed to the ISO number: ISO 200 gives 1/250. Cameras round to the nearest click, so 1/200 or 1/250 both work.
Does the Sunny 16 rule work on cloudy days?
Yes, with the variations. Open one stop for slight haze (f/11), two for bright overcast (f/8), three for heavy overcast (f/5.6), and four for open shade (f/4). The shutter speed stays at 1 over ISO.
Why are my sunny day photos too dark even at f/16?
Usually the shutter is faster than 1 over ISO, or the scene fooled you. Check that the shutter speed matches the ISO, and remember the rule assumes frontlit subjects in midday sun, not backlit scenes or late evening light.
Can I use the Sunny 16 rule on my phone?
The idea transfers, but most phones choose exposure automatically and hide the settings. The rule is most useful on cameras where you set aperture, shutter speed, and ISO yourself.
Is the Sunny 16 rule still useful with a digital camera?
Yes, as a sanity check and a starting point. If your meter suggests something wildly different from Sunny 16 in bright sun, one of your settings is off. It also teaches the exposure triangle faster than any menu.