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Sunny 16 rule

Sunny 16 rule is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sunny 16 rule rather than just read about it. In short: In photography, the sunny 16 rule (also known as the sunny f/16 rule) is a method of estimating correct daylight exposures without a light meter. Apart from the advantage of independence from a light meter, the sunny 16 rule can also aid in achieving correct exposure of difficult subjects.

Sunny 16 rule — main illustration
Sunny 16 rule — illustration

Key takeaways

  • Sunny 16 rule belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Sunny 16 rule to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Sunny 16 rule from memory before moving on to harder problems.

Reference excerpt

In photography, the sunny 16 rule (also known as the sunny f/16 rule) is a method of estimating correct daylight exposures without a light meter. Apart from the advantage of independence from a light meter, the sunny 16 rule can also aid in achieving correct exposure of difficult subjects. As the rule is based on incident light, rather than reflected light as with most camera light meters, very bright or very dark subjects are compensated for. The rule serves as a mnemonic for the camera settings obtained on a sunny day using the exposure value (EV) system.

Using the rule The basic rule is, "On a sunny day set aperture to f/16 and shutter speed to the [reciprocal of the] ISO film speed [or ISO setting] for a subject in direct sunlight." In simplest terms, bright sun = f:16 @ 1/film-speed-number (aperture and shutter speed, respectively). For example:

On a sunny day at ISO 100 ("100 speed film"), the aperture is set to f/16 and the shutter speed (i.e. exposure time) to ⁠1/100⁠ or ⁠1/125⁠ seconds (on some cameras ⁠1/125⁠ second is the closest available setting to ⁠1/100⁠ second). On a sunny day at ISO 200 and aperture at f/16, set shutter speed to ⁠1/200⁠ or ⁠1/250⁠. On a sunny day at ISO 400 and aperture at f/16, set shutter speed to ⁠1/400⁠ or ⁠1/500⁠. Shutter speeds can be changed as long as the f-number is adjusted accordingly, e.g. ⁠1/250⁠ second at f/11 gives equivalent exposure to ⁠1/125⁠ second at f/16. Exposure adjustments are done in a manner that retains the EV. As the aperture is opened (f:11, f:8, f:5.6, f:4, etc.) the shutter-speed/exposure-time is reduced by a factor of approximately one-half (1/250, 1/500, 1/1000, etc.) This follows the mathematical relationship between aperture and shutter speed where exposure is inversely proportional to the square of the aperture ratio and proportional to exposure time; thus, to maintain a constant level of exposure, a change in aperture by a factor c requires a change in exposure time by a factor ⁠1/c2⁠ and vice versa. A change in the aperture of 1 stop always corresponds to a factor close to square root of 2, thus the above rule.

Alternative rule The sunny 16 rule can be used in varying light by setting the shutter speed nearest to the ISO film speed and f-number according to a generalized exposure table, as:

See also Looney 11 rule

References

External links Guide to Photography Sunny 16 and film exposure guide.

Illustrations

Sunny 16 rule: Sunlit subject shot on a digital camera set to ISO 100, exposed at f/8 at 1/400 second which is the same exposure value as f/16 for 1/100 second, the recommended "sunny 16" exposure
Sunlit subject shot on a digital camera set to ISO 100, exposed at f/8 at 1/400 second which is the same exposure value as f/16 for 1/100 second, the recommended "sunny 16" exposure
Sunny 16 rule: Tessina with exposure guide plate from the 1960s. At that time, DIN 21 was equivalent to ASA 80. After 1983, DIN 21 was ASA 100.[5] On this guide plate, DIN 21 uses f/16 and 1/125, consistent with Sunny 16.
Tessina with exposure guide plate from the 1960s. At that time, DIN 21 was equivalent to ASA 80. After 1983, DIN 21 was ASA 100.[5] On this guide plate, DIN 21 uses f/16 and 1/125, consistent with Sunny 16.

Worked examples

Example 1 — a first encounter with Sunny 16 rule

Start with the simplest possible case. Write down what Sunny 16 rule claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sunny 16 rule before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sunny 16 rule ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sunny 16 rule

In research
Sunny 16 rule appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Sunny 16 rule in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Sunny 16 rule is common in secondary-school and first-year university syllabi. It links to neighbouring topics Photographic techniques, Rules of thumb, so understanding it makes those chapters shorter.
In everyday life
Look for Sunny 16 rule outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Sunny 16 rule in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Sunny 16 rule means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Sunny 16 rule out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sunny 16 rule in simple terms?

In photography, the sunny 16 rule (also known as the sunny f/16 rule) is a method of estimating correct daylight exposures without a light meter. Apart from the advantage of independence from a light meter, the sunny 16 rule can also aid in achieving correct exposure of difficult subjects.

Why does Sunny 16 rule matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sunny 16 rule?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sunny 16 rule.

Tags

  • Photographic techniques
  • Rules of thumb

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