What is the rule of thirds?

This week's Photography Fundamentals column digs into composition, and one of the most-cited 'rules' of the discipline: the rule of thirds. Even if you don't know what it is, you've probably heard of it. We are, therefore, here to explain what it is and why it's useful. And then when you understand the rule and you know how to implement it, you can go ahead and break it properly. We have a natural tendency to place our subjects in the centre of the frame. It makes sense, logically, to have our point of focus right in the middle, being gloried by its surroundings and utterly unavoidable to the eye. Except that centred subjects don’t really make for very interesting images. There’s an unmistakable flat and dull quality to them. Compare this:

With this:

Next time you’re watching a film or TV, notice where the heads and the eyes of the people doing the talking are. I’ll bet they’re not in the centre of the frame.

Instead, they’ll be positioned slightly to one side. They’ll probably be making use of what’s called the rule of thirds.

Imagine that your frame is divided by four lines: two running horizontally and two vertically. They are equally spaced and split the frame into nine smaller rectangles. The points at which the four lines intersect create four ‘points of interest’. This grid is your guide for composing an image.

Aim to position subjects that run upright through your image along one of the vertical tri-lines. Lines running across the image—especially skylines and horizons—should run along a horizontal tri-line. (Definitely not through the centre with a horizon.)

Aim to place anything that’s of particular significance to the composition, for example the eyes in a portrait and the sun in a sunset scene, on one of the points of interest.

Variations

I often find that rather than using the rule of thirds to place my subjects, I have a natural predeliction for the Golden Rectangle. It's based on the mathematical princple of the Golden Ratio: an irrational number equal to approximately 1.618. It's also known as Phi (φ). If you want the technical explanation, it's

If you divide a line unevenly into two sections a (longer) and b (shorter), the ratio of these two sections will equal φ if a divided by b is equal to the sum of a plus b divided by a.

Yes. Ahem.

Rather than divide your frame using three equally spaced lines along each edge, as you would with the rule of thirds, you have two longer sections (a) either side of a shorter section (b). The ratio of the longer side to the shorter is the golden ratio.

It looks like this:

Square crops

If you're using a square crop for any of your photos, you might find that the rule of thirds doesn't produce the sort of dynamic image that you're used to with a rectangular frame. That's because the eye tends to move around a square photo, rather than across it. For this reason, centred subjects often work effectively in square frames. Or try dividing the frame into triangles, and using those for balance.

TL;DR

• The rule of thirds is a compositional aid that places two equally spaced lines across your frame, and two down it
• The horizontal lines can be used for the strong placement of horizons and skylines
• The vertical lines can be used to position key vertical elements in your frame
• The four points at which the lines intersect are known as 'points of interest'
• Use the points of interest to place significant elements of your composition, for example the eyes in portraits or the sun in sunsets, in your frame
• There are variations on the rule of thirds, based on the mathematical principle φ
• The rule of thirds doesn't necessarily work with a square crop; you might find a centred subject works better

Quality vs quantity << Photography Fundamentals >> Speed

Image aspect ratios

In a recent photo critique, I went off on one about the aspect ratios I prefer, when I look at photos. But have you ever thought about why you would prefer a particular image ratio? Is there a rule about what size photos should be, and if so – who decides the rules?

I’m just sharing my own thoughts here, but I’d love to hear your opinions on the matter as well!

There are a lot of ideas around regarding what size things should be. ISO 7810, for example, specifies the size and shape of a credit card, the aspect ratio of which many people find is a comfortable, conceivably because its official size (85.60 × 53.98 mm) is pretty close to the aspect ratio of a golden rectangle (related, of course, to the golden ratio. See also the silver ratio, which is used, among other things, to determine the shape of an A4 sheet of paper).

So why do most photographers operate with 3:2, 4:3 or 1:1? Well, truth be told, it’s a historical thing: The modern 135 film (also known as 35mm – referring to the width of the film – or 36mm – referring to the width of a negative frame – film) was 36mm by 24mm in size. The past 80 years or so, we have become so accustomed to the 36×24 (that is to say, 3:2 aspect ratio) photos, that it just looks… right.

4:3 is the aspect ratio of a normal television, which is of course another size we have become used to over time, and it is the aspect ratio used by most computer monitors. Some digital camera manufacturers took to – including Canon: my Digital Ixus / Elph takes photos in the 4:3 aspect ratio. Some cameras – including the Canon Powershot G7 – even support both image ratios, selectable in the menu system. If you are curious which cameras use which aspect ratio, check out Digital Photo Review. Since the dawn of time (well, since Phil Askey has had the the stats on his site), they’ve kept track of which camera uses which.

The last aspect ratio that is popular is 16:9, because it is used in cinemas as ‘wide screen’, but there are dozens of others in use, too.

So, err, do you use a calculator when you crop your photos?

Oh, not at all! The marquee tool in Photoshop has a powerful function which is called ‘fixed aspect ratio’. As you probably know, if you use the marquee tool and hold the shift key, the selected area is forced to be a perfect square. You can also select your own aspect ratio, however, in the tool menu that shows up when you select the marquee tool:

Here, you can type in whatever aspect ratio you prefer, and the select tool will lock on to it. If you want to switch between 3:2 and 2:3 (for example, if you want to crop portrait instead of landscape photos), you can just click the button with the two little arrows: It swaps the numbers over for you.

Nifty, yes?

What makes you choose an aspect ratio over another?

So, why do I refuse to crop images to anything other than either 3:2? It’s an odd one, I’m fully aware of that, but to me, there’s something almost holy about 3:2. I like my photos to be photo-shaped, and to me, the 3:2 shape just looks the most right. I find it peaceful to look at, and there is something exciting about working to the arbitrary and dated restraint of 3:2.

At the same time, I did a photo shoot about 4 years ago which opened my eyes to shooting square photos. I had a few photographs that were very successful, but that just didn’t quite want to work out as photos. In the end, I spotted that perhaps it would work if it was square, and this was the result:

Ultimately, I can’t tell why I decided to stick to those two formats. Perhaps it looks tidier. Perhaps it saves time if and when I decide to have the photos printed. Or perhaps I’m just an old-fashioned has-been, who refuses to let the fact that you can crop your image to whatever the hell you want to break on through.

So… What about you? Do you have hang-ups about aspect ratios of your images? Leave a comment!

(can you spot what all the aspect ratios in this post were? The girl is 1:1, the glasses and sleepy person is 3:2, the flower is 4:3, and the brown stuff, which actually is tobacco from a cigarette, magnified 6x, is 16:9)

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