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Rule of thirds

Rule of thirds 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 Rule of thirds rather than just read about it. In short: The rule of thirds is a rule of thumb for composing visual art such as designs, films, paintings, and photographs. The guideline proposes that an image should be imagined as divided into nine equal parts by two equally spaced horizontal lines and two equally spaced vertical lines, and that important compositional elements should be placed along these lines or their intersections.

Rule of thirds — main illustration
Rule of thirds — illustration

Key takeaways

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

Reference excerpt

The rule of thirds is a rule of thumb for composing visual art such as designs, films, paintings, and photographs. The guideline proposes that an image should be imagined as divided into nine equal parts by two equally spaced horizontal lines and two equally spaced vertical lines, and that important compositional elements should be placed along these lines or their intersections. The theory is that aligning a subject with these points creates more tension, energy and interest in the composition than simply centering the subject.

Use The rule of thirds is applied by aligning a subject with the guide lines and their intersection points, placing the horizon on the top or bottom line, or allowing linear features in the image to flow from section to section. The main reason for observing the rule of thirds is to discourage placement of the subject at the center, or prevent a horizon from appearing to divide the picture in half. Michael Ryan and Melissa Lenos, authors of the book An Introduction to Film Analysis: Technique and Meaning in Narrative Film, state that the use of rule of thirds is "favored by cinematographers in their effort to design balanced and unified images". When filming or photographing people, it is common to line the body up to a vertical line and the person's eyes to a horizontal line. If filming a moving subject, the same pattern is often followed, with the majority of the extra room being in front of the person (the way they are moving). Likewise, when photographing a still subject who is not directly facing the camera, the majority of the extra room should be in front of the subject with the vertical line running through their perceived center of mass.

History

The expression "rule of thirds" was first written down by John Thomas Smith in 1797. In his book Remarks on Rural Scenery, Smith quotes a 1783 work by Sir Joshua Reynolds, in which Reynolds discusses, in unquantified terms, the balance of dark and light in a painting. John Thomas Smith then continues with an expansion on the idea, naming it the "rule of thirds":

Two distinct, equal lights, should never appear in the same picture : One should be principal, and the rest subordinate, both in dimension and degree: Unequal parts and gradations lead the attention easily from part to part, while parts of equal appearance hold it awkwardly suspended, as if unable to determine which of those parts is to be considered as the subordinate. "And to give the utmost force and solidity to your work, some part of the picture should be as light, and some as dark as possible: These two extremes are then to be harmonized and reconciled to each other." (Reynolds' Annot. on Du Fresnoy.)

Analogous to this "Rule of thirds", (if I may be allowed so to call it) I have presumed to think that, in connecting or in breaking the various lines of a picture, it would likewise be a good rule to do it, in general, by a similar scheme of proportion; for example, in a design of landscape, to determine the sky at about two-thirds; or else at about one-third, so that the material objects might occupy the other two : Again, two thirds of one element, (as of water) to one third of another element (as of land); and then both together to make but one third of the picture, of which the two other thirds should go for the sky and aerial perspectives. This rule would likewise apply in breaking a length of wall, or any other too great continuation of line that it may be found necessary to break by crossing or hiding it with some other object : In short, in applying this invention, generally speaking, or to any other case, whether of light, shade, form, or color, I have found the ratio of about two thirds to one third, or of one to two, a much better and more harmonizing proportion, than the precise formal half, the too-far-extending four-fifths—and, in short, than any other proportion whatever. I should think myself honored by the opinion of any gentleman on this point; but until I shall by better informed, shall conclude this general proportion of two and one to be the most pictoresque medium in all cases of breaking or otherwise qualifying straight lines and masses and groupes [sic], as Hogarth's line is agreed to be the most beautiful, (or, in other words, the most pictoresque) medium of curves. Writing in 1845, in his book Chromatics, George Field notes that Sir Joshua Reynolds gives the ratio 2:1 as a rule for the proportion of warm to cold colors in a painting, and attributes to Smith the expansion of that rule to all proportions in painting:

Sir Joshua has given it as a rule, that the proportion of warm to cold colour in a picture should be as two to one, although he has frequently deviated therefrom; and Smith, in his "Remarks on Rural Scenery," would extend a like rule to all the proportions of painting, begging for it the term of the "rule of thirds," according to which, a landscape, having one third of land, should have two thirds of water, and these together, forming about one-third of the picture, the remaining two-thirds to be for air and sky; and he applies the same rule to the crossing and breaking of lines and objects, &c.

Even at this early date, there was skepticism over the universality of such a rule, at least in regards to color, for Field continues:

This rule, however, does not supply a general law, but universalises a particular, the invariable observance of which would produce a uniform and monotonous practice. But, however occasionally useful, it is neither accurate nor universal, the true mean of nature requiring compensation, which, in the case of warmth and coolness, is in about equal proportions, while, in regard to advancing and retiring colours, the true balance of effect is, approximately, three of the latter to one of the former; nevertheless, the proportions in both cases are to be governed by the predominance of light or shade, and the required effect of a picture, in which, and other species of antagonism, the scale of equivalents affords a guide. Although the rule of thirds is widely supported by filmmakers and directors such as the famous "Steven Spielberg", the "rule" is believed to enhance depth and composition in images and films, and has also been supported through data gathered using a Likert-scale questionnaire. Returning to Smith's perspective, his discussion of this "rule" is independent of the history and use of the term in composition and photography.

… excerpt ends here. Continue reading the full article.

Illustrations

Rule of thirds: The photograph demonstrates the application of the rule of thirds. The horizon in the photograph is on the horizontal line dividing the lower third of the photo from the upper two-thirds.  The tree is at the intersection of two lines, sometimes called a power point[1] or a crash point.[2]
The photograph demonstrates the application of the rule of thirds. The horizon in the photograph is on the horizontal line dividing the lower third of the photo from the upper two-thirds. The tree is at the intersection of two lines, sometimes called a power point[1] or a crash point.[2]
Rule of thirds: A picture cropped without and with the rule of thirds
A picture cropped without and with the rule of thirds
Rule of thirds: Excerpt from John Thomas Smith's illustrated book, published in 1797, defining a compositional "rule of thirds"
Excerpt from John Thomas Smith's illustrated book, published in 1797, defining a compositional "rule of thirds"

Worked examples

Example 1 — a first encounter with Rule of thirds

Start with the simplest possible case. Write down what Rule of thirds 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 Rule of thirds 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 Rule of thirds 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 Rule of thirds

In research
Rule of thirds 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 Rule of thirds 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
Rule of thirds is common in secondary-school and first-year university syllabi. It links to neighbouring topics Composition in visual art, Photographic techniques, Rules of thumb, so understanding it makes those chapters shorter.
In everyday life
Look for Rule of thirds 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 Rule of thirds in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Rule of thirds 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 Rule of thirds out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rule of thirds in simple terms?

The rule of thirds is a rule of thumb for composing visual art such as designs, films, paintings, and photographs. The guideline proposes that an image should be imagined as divided into nine equal parts by two equally spaced horizontal lines and two equally spaced vertical lines, and that importan…

Why does Rule of thirds 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 Rule of thirds?

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 Rule of thirds.

Tags

  • Composition in visual art
  • Photographic techniques
  • Rules of thumb

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