Aspect ratio is something to which many people don’t give a great deal of thought, but it can make a big difference – both to your shots and then when it comes to printing. Many cameras now allow you to change the aspect ratio of your shots via the menu system, but even if yours doesn’t, you can change the aspect ratio later simply by cropping in a photo editing program.

What is the aspect ratio?

Put simply, the aspect ratio is the ratio of the width of your image to its height. If your image is four units long and three units deep, it would have an aspect ratio of 4:3. This is one of the most common formats, with the next most common being 3:2 – the majority of DSLRs have a 3:2 ratio. The default aspect ratio is normally dependent on the size and shape of the camera’s digital sensor.
To understand how the figures are arrived at, let’s look at an easy example. A full-frame 35mm sensor measures 36mm x 24mm and you can express this as a ratio of 36:24. However, it’s much better to simplify the ratio so that it’s easier to visualise, and in this case you can divide both figures by 12, giving you 3:2. The majority of cameras don’t have full-frame sensors and typically the sensor size might be something like 22.5mm x 15mm. The sums are a bit more difficult to do, but if you feel like doing the maths you’ll find that these figures also conform to the 3:2 aspect ratio…

View or download our full article as a pdf document: Aspect Ratios