Sunny 16 Rule. How & Why to Use It in Modern Photography

There are a lot of different rules and guidelines in photography to help make the photographer’s job easier. The Sunny 16 Rule is one such suggestion, intended to make reaching perfect exposure in bright conditions easier.

Sunny 16 Rule. How & Why to Use It Modern Photography

If you do a lot of outdoor photography, you’ll often find that shooting at high sun times (like noon, for example) is particularly difficult and harsh- but Sunny 16 is here to help!

What is the Sunny 16 Rule?

The Sunny 16 Rule states that when you are using an aperture (or f-stop) of f/16 on a clear sunny day, you are encouraged to use a shutter speed that is the same as your ISO value.

For example, if your ISO is set to 100, you use a shutter speed of 1/100. If your ISO is 400, you use a shutter speed of 1/400, and so forth.

That being said, keep in mind that not all worthwhile, such as an ISO of 3200 shot with a shutter speed of 1/3200 (you’d never need such a high ISO on a bright sunny day).

The Sunny 16 Rule is intended to be a quick photographer’s guide to some simple settings for a good exposure.

Exposure is the amount of light that reaches your sensor.

Too much exposure (overexposure) causes your photograph to be too bright while not enough exposure (underexposure) causes your image to be too dark. This rule aims to help you find the perfect middle.

the photo of the California Highway 1 in Big Sur on sunny afternoon
The weather conditions when the Sunny 16 Rule is applied (f/16, 1/60s, ISO100)

Expanding on the Sunny 16 Rule

The Sunny 16 Rule is not an end-all-be-all. There are ways to expand upon this rule. You can use Sunny 16 to calculate the relationship between other aperture values and the shutter speed and ISO values.

Remember about the relationship between aperture, shutter speed, and ISO, also known as Exposure Triangle.

If you increase or decrease any one of these variables, the others must increase or decrease in order to keep the exposure the same. A quick guide to remember how these variables affect exposure is as follow:

  • Wide aperture (smaller number) = Lighter image.
  • Narrow aperture (larger number) = Darker image.
  • Fast shutter speed (larger number) = Darker image.
  • Slow shutter speed (smaller number) = Lighter image.
  • High ISO (larger number) = Lighter image.
  • Low ISO (smaller number) = Darker image.

If one factor goes up by one stop, another factor should go down by one stop. The most common examples are as such:

  • f/16 – 1/100s – ISO100 – Basic Sunny 16 Rule
  • f/11 – 1/200s – ISO100 – Modified Sunny 16 Rule (aperture +1 stop, shutter speed -1 stop)

On Fujifilm cameras, the basic ISO is 200 and I need to adjust my Sunny 16 Rule to reflect it.

  • f/8 – 1/800s – ISO200 – (aperture +2 stops, shutter speed -3 stop, ISO +1 stop)

Variations of the Sunny 16 Rule

There are variations to the Sunny 16 Rule that can be applied to different weather conditions. As you can imagine, you won’t always have a perfectly clear sunny day (even in Southern California!). These variations come in the form of different apertures:

  • Snowy or sandy conditions: f/22
  • Clear and sunny conditions: f/16
  • Slightly overcast: f/11
  • Overcast: f/8
  • Heavy overcast: f/5.6
  • Open shade or sunset: f/4

It does not mean that I have to use f/22 when photographing snowy scenes. I more likely to adjust the Sunny 16 Rule to the following numbers: f/11 – 1/800s – ISO200 (aperture +2 stops, shutter speed – 3 stops, ISO +1 stop, Fujifilm remember?)

Once again, the Sunny 16 Rule is a guideline only.

Do We Need the Sunny 16 Rule with Modern Cameras?

The Sunny 16 Rule originated in film days when cameras did not have internal light meters. In modern times, some consider this rule a relic, but it can still hold true today.

Related: How to Master Histogram in Photography

The Sunny 16 Rule is based on the brightness of light only and not how that light is being reflected by the objects. This light is called incident light (instead of reflective light). This means that the Sunny 16 Rule, not like light meter inside of the camera, cannot be fooled by an object being too bright or too dark on a contrasting background that can fool the system.

You can use the Sunny 16 Rule even with modern cameras to make sure that your light meter inside of the camera is not getting thrown off. This is just some extra insurance on your exposure just in case your meter is wrong.

Modified Suuny 16 Rule: f/8, 1/400s., ISO100

The Sunny 16 Rule and Lenses

There is a catch to the Sunny 16 Rule with regards to the notion of “sweet spot.”

The sweet spot of a lens is the aperture value (f-stop number) that is considered to produce optimally sharp photos with the least amount of distortion and fringing and the best sharpness. It varies from one lens model to another.

For some lenses, narrowing the aperture to f/16, doesn’t allow the lens to reach its optimal performance because the lens is best used at f/8, for example. Just keep this in mind that it is a good idea to adjust the Sunny 16 Rule to match your lens “sweet spot.”

Alongside this, the Sunny 16 Rule doesn’t follow the aesthetic of shallow depth of field (DoF). Shallow depth of field is when a subject is in clear focus and the background melts away in a blur.

Related: How to Know What Aperture to Use

Shallow depths of field is achieved when the aperture of a lens is at its widest point or lowest f/number. The aperture of F/16 produces a much larger depth of field that means more will be in focus, so it is impossible to achieve a shallow depth of field here.

Final Thoughts on the Sunny 16 Rule

In conclusion, the Sunny 16 Rule is more of a baseline that you can build upon or detract from depending on the equipment that you use or the shooting conditions you are in. This is meant to be a guideline to ease your work as a photographer, but it is not mandatory!

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by Viktor Elizarov
I am a travel photographer and educator from Montreal, Canada, and a founder of PhotoTraces. I travel around the world and share my experiences here. Feel free to check my Travel Portfolio and download Free Lightroom Presets.