In bright sun, start at f/16 with a shutter time near the reciprocal of ISO. At ISO 100 that means about 1/100 second; 1/125 is a common nearby setting. Sunny 16 estimates exposure from the light on the subject. It is a starting point, not a promise that every sunny scene has identical illumination.
Download the one-page Sunny 16 chart (PDF) or open the full-size image chart.
| Light on the subject | Starting aperture | ISO 100 | ISO 200 | ISO 400 |
|---|---|---|---|---|
| Bright sun, distinct shadows | f/16 | 1/125 s | 1/250 s | 1/500 s |
| Hazy sun, soft shadows | f/11 | 1/125 s | 1/250 s | 1/500 s |
| Bright overcast, little shadow | f/8 | 1/125 s | 1/250 s | 1/500 s |
| Heavy overcast or open shade | f/5.6 | 1/125 s | 1/250 s | 1/500 s |
These are approximate traditional starting points. Deep shade can need more exposure than open shade. Backlight, cloud thickness, reflections and the subject’s tone all change the result. With digital capture, inspect the important highlights and subject detail. With film, consult the specific stock’s exposure guidance and record any bracketed frames.
Change aperture without changing exposure
| ISO 100 in the same light | Approximate equivalent shutter |
|---|---|
| f/16 | 1/125 s |
| f/11 | 1/250 s |
| f/8 | 1/500 s |
| f/5.6 | 1/1000 s |
| f/4 | 1/2000 s |
Each wider full stop doubles the light per unit time; halving the shutter time compensates. If your camera runs out of shutter speed, use a smaller aperture, lower ISO where appropriate, or a suitable ND filter. The exposure triangle guide explains the tradeoffs.
Sunny 16 is not the handholding reciprocal rule
Sunny 16 estimates exposure using ISO and illumination. The handholding guideline estimates a shutter speed to reduce camera shake using focal length, with qualifications for format, stabilization and viewing size. Neither guarantees a sharp moving subject. At 1/100 second a long lens can still show shake even when the exposure is correct.
Video and ND: count both changes
At 24 frames per second, a 180-degree shutter corresponds to 1/48 second; 1/50 is a nearby available setting. Suppose your daylight reference is ISO 100, f/16, 1/100 second. Opening to f/2.8 adds about five stops, and lengthening to 1/50 adds one more. You need approximately six stops of ND, commonly described as optical density 1.8 or a 64× factor.
If your reference was 1/125 rather than 1/100, the total is about 6⅓ stops. Closing from f/16 to f/22 removes about one stop, not 1⅓. These calculations explain the starting adjustment; check the actual filter, camera and scene for exposure and color casts.
What about the Moon?
The Moon is sunlit, but it is not an ordinary average daylight subject. Phase, atmospheric haze, focal length and the detail you want to retain affect exposure. The traditional “Looney 11” estimate starts near f/11 and 1/ISO for a bright Moon; treat it as a bracketable estimate, not a guaranteed setting or a substitute for checking lunar highlights. Use the Moon photography guide for the full workflow.
Read the light on the subject
A bright sky does not mean the person beneath a tree receives bright direct sunlight. Look at the light falling on the part of the subject you want to expose. A distinct, hard-edged shadow is a useful clue for the bright-sun starting point; a subject facing away from the sun presents a different problem from one lit on the camera-facing side.
The Kodak TRI-X technical data provides daylight starting settings distinguished by shadow quality and includes separate bright-sand/snow guidance. Its values are recommendations for the named film, not a meter reading for every outdoor scene. Use your film’s own data when available.
Set ISO deliberately before comparing exposures
For a manual digital exercise, fix ISO as well as aperture and shutter time. With Auto ISO active, the camera may change ISO while you adjust another setting, making the comparison different from the one you intended. Check the recorded values rather than assuming all frames used the same sensitivity setting.
For film, the roll has a specified speed. Turning an ISO dial changes the meter’s recommendation; it does not physically change the film already loaded. If you deliberately expose at a different index, record it and agree any processing implications with the lab rather than treating each frame as a separate digital ISO choice.
Why a meter and Sunny 16 may disagree
Sunny 16 estimates from illumination. A reflected-light meter responds to light coming back from the scene and to its metering pattern. A very bright or very dark area can influence the reading, and a backlit subject can place bright background and shadowed face in the same frame.
First check that both estimates refer to the same subject and light. Then check ISO, filters, exposure compensation and camera mode. A difference does not automatically mean the meter is broken or the rule is wrong. Decide which detail matters and evaluate whether the exposure preserves it.
Bracket in a way you can interpret
For a static exercise at ISO 100 and f/16, a nominal 1/125-second frame can be compared with 1/60 and 1/250. Those neighboring settings give approximately one stop more and one stop less exposure. Keep the subject and lighting as consistent as possible and label the frames.
If subject motion is the priority, changing shutter time also changes blur. Use a different controlled adjustment if that would obscure the exposure lesson. With film, keep a frame-number record; with digital, retain the original files and exposure metadata. A processed preview may hide differences that become apparent in the original capture.
When to stop relying on the estimate
Use a more specific measurement or test when the subject is indoors, lit by mixed sources, strongly backlit or placed in deep shade. The chart’s short labels cannot describe every combination of cloud, reflection and orientation. A sunset is especially variable: the sun itself, the sky and a person in the foreground need not share one useful exposure.
Finally, separate brightness from sharpness. A correctly exposed frame can still have missed focus, camera shake or subject blur. Correct that cause instead of changing exposure merely because the photograph looks disappointing.
Make the estimate useful in the field
Record the light description, ISO, aperture, shutter and what your meter recommended. Compare bright sun, open shade and overcast conditions at the same location. This article does not present those captures as completed tests. For lunar photography, Nikon’s Moon-photography guidance recommends checking lunar detail and bracketing rather than assuming a generic night exposure will work.
