Before digital cameras with sophisticated metering systems, photographers needed a reliable way to estimate correct exposure in the field. The Sunny 16 rule has been that trusted companion for over a century—and it still works perfectly today.
Whether you're shooting film, testing a vintage camera, or simply want to understand exposure at a deeper level, mastering Sunny 16 will make you a more confident photographer.
What Is the Sunny 16 Rule?
The Sunny 16 rule states: On a sunny day, set your aperture to f/16 and your shutter speed to the reciprocal of your ISO.
That's it. Simple and elegant.
For example:
- At ISO 100: f/16 at 1/100s (or 1/125s)
- At ISO 200: f/16 at 1/200s (or 1/250s)
- At ISO 400: f/16 at 1/400s (or 1/500s)
- EV 16: Bright sand or snow in full sun
- EV 15: Sunny, clear sky (Sunny 16 baseline)
- EV 14: Hazy sun, soft shadows
- EV 13: Cloudy bright, no shadows
- EV 12: Heavy overcast
- EV 11: Open shade on a sunny day
- EV 10: Shade, twilight just before dark
- EV 8-9: Bright indoor lighting
- EV 5-7: Indoor home lighting
- EV 3-4: Candles, Christmas lights
- Street photography: Quick shots without fiddling with settings
- Film photography: Especially with cameras that have no meter
- Vintage cameras: Testing exposure accuracy
- Backup method: When your meter fails or batteries die
- Learning: Understanding the relationship between light and exposure
This gives you a correctly exposed image in bright sunlight with hard shadows.
Adapting for Different Light Conditions
The real power of Sunny 16 comes from understanding how to adjust it for other lighting situations. Each stop of light difference means opening up one stop or slowing down your shutter.
The Full Exposure Chart
f/16 — Sunny, bright with hard shadows
f/11 — Slight overcast, soft shadows visible
f/8 — Overcast, no shadows visible
f/5.6 — Heavy overcast, or open shade
f/4 — Dusk, deep shade, or just after sunset
You can also think of this as EV (Exposure Value) adjustments. Bright sun is EV 15 at ISO 100. Each condition change is roughly one EV step.
Understanding Exposure Values (EV)
Exposure Values provide a more precise way to describe lighting conditions. Every EV number represents a specific amount of light, and each step up or down is exactly one stop.
Here's how common situations map to EV (at ISO 100):
Once you know the EV, you can pick any aperture/shutter combination that adds up to that value.
Practical Tips for Using Sunny 16
1. Look at the Shadows
The quickest way to judge light is to look at shadows. Hard, defined shadows mean Sunny 16 territory. Soft shadows mean open up. No shadows? Open up even more.2. Trust It for Film
Film has remarkable latitude, especially negative film. If you're within one stop, you'll get a usable image. Sunny 16 is more than accurate enough.3. Use It as a Sanity Check
Even with a digital camera, Sunny 16 helps you spot when your meter might be fooled by backlighting, reflections, or unusual scenes.4. Practice Without Your Camera
When you're walking around, mentally estimate the exposure based on conditions. Check against your phone's camera app. You'll internalize it quickly.When Sunny 16 Shines
The Modern Photographer's Take
In an age of matrix metering and Auto ISO, why bother with Sunny 16?
Because understanding light is what separates photographers from camera operators. When you know that a scene is about EV 12, you make better creative decisions. You anticipate problems. You work faster.
Sunny 16 isn't just an exposure trick—it's a lens (pun intended) for seeing light the way your camera does.
Try It Yourself
Use our Sunny 16 Calculator to practice converting between lighting conditions, EVs, and camera settings. It includes three modes: quick Sunny 16 estimates, EV-to-settings conversion, and settings-to-EV calculation.
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The Sunny 16 rule dates back to the early 20th century and was printed on film box inserts for decades. It remains as accurate today as it was then—because sunlight hasn't changed.