When you are interested in photography you will start reading books on the subject or browsing the web. Eventually you will encounter the rule of thirds. Or maybe, when playing around with your camera settings, you found this grid you can overlay on your screen or viewfinder. You may have wondered about the use of it. Both have to do with picture composition and creating appealing pictures.

What is this rule of thirds?

For applying the rule of thirds you are supposed to divide the screen/picture in nine equal segments by dividing the horizontal and vertical sides in three equal parts. Then, if you place your main subject on the intersection of any of the horizontal and vertical lines, you will have created a composition that is appealing to most human beings. In the examples underneath I show two examples where I first placed the main subject in the centre and then moved it to one or two of the intersection points.

For most people the pictures on the right are more appealing than the ones on the left. How come? It all has to do with the ‘divine proportion’ or divine section, golden ratio, or golden cut.

The divine proportion

The divine proportion is a ratio of dimensions that is encountered in nature in e.g. the positions of branches along the stem of a plant, the veins in leaves and the proportions of the different body parts of a human. Mathematically, the golden ratio determines how the lengths of two line segments relate to each other.

If in the above figure the lengths a and b relate to each other identically as the lengths a+b and a, or put in an equation a/b = (a+b)/a, then the ratio of a and b is called the golden ratio. Working out the math yields that a/b = 1.61803…, the dots meaning that there is an infinite number of decimals.

If we now make a rectangle having horizontal size a+b as in the above line segment and vertical size a, the lengths of the sides of the rectangle have the divine proportion. Then, applying this divine proportion to the horizontal length results in a smaller (standing) rectangle that also has the divine proportion, see the figure underneath.

We can divide the small rectangle in two smaller ones, again having the divine proportion. The dividing of the large rectangle in smaller ones can of course be done in different directions. If we do this two levels deep and connect the line segments, we get the structure as shown below. The crossings of the horizontal and vertical lines are the golden cuts.

Our eyes, when looking at a scene, will by instinct scan the divine proportion positions, i.e. the crossings of the horizontal and vertical lines. Thus, positioning the subjects we photograph there will in general lead to compositions that are considered as appealing.

The easy way out

Since it is practically impossible to mentally divide a scene up in parts of which the lengths relate to each other as 1.61803… (at least it is for me and I’m a nerd), we aren’t that far off if we divide in thirds instead, see the figure underneath.

The purists among us will opt for the real golden cut. For me, the rule of thirds is good enough. And then, this ‘rule’ is not carved in stone. It’s more like a guideline. If your main object is somewhere near one of the thirds lines and / or intersections, it’s OK.

A few more examples:

Conclusion

One final thing: As with all rules, being too strict about it will be counterproductive. So let’s not call it ‘the rule of thirds’ anymore but rather ‘the suggestion of thirds’.