A beginner's guide to aspect ratio and how to use it to compose stunning images

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Aspect ratio is a crucial element in photography, but it’s usually something that not many of us fully understand. So, what is it in the first place, and why does it matter?

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Photo by RawPixel

In simplest terms, aspect ratio is the relationship between the width and the height of an image. The reason it's so essential is because it influences how you compose your photograph and how big it’s going to be. Here, we’ll discuss common questions people have about it, and how it can be applied effectively in photography.

01. What is aspect ratio?

Aspect ratio is primarily dictated by the size of your camera's sensor, taken from the width and height of an image (W:H). For instance, if your camera sensor is 36mm wide and 24mm high, its aspect ratio would be 3:2 (not 36mm x 24mm).

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Photo by Ryan Hafey

Back then, aspect ratios didn’t matter much to most photographers since they were stuck with whatever format their device used. If they had a medium format camera, then they took square-sized (1:1) photographs. And if they had a 35mm version, they had rectangle images (3:2) instead.

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Photo by César Guadarrama Cantú

Some formats that prevailed during the era of film photography have carried over to their digital counterparts today. For instance, the 3:2 format is still used by modern full-frame DSLRs. Meanwhile, 1:1 or 4:3, which were common among medium format, have also been adopted digitally.

These days, however, most modern cameras don’t feature just one format, but two or even more—whether it be square, rectangle, or even panoramic.

02. What are the popular aspect ratio formats?

3:2

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Photo by Ian Dooley

As mentioned, professional, full-frame digital cameras still conform to the 3:2 size based on the 35mm film frame. However, advanced photo system type-C (APS-C) crop sensors from entry-level DSLRs also use the same aspect ratio despite being smaller than their full-frame counterparts. Canon’s 22.20mm x 14.80mm and Nikon’s 23.6 (or 23.7mm x 15.60mm) APS-C sensors are both smaller than the full frame 36 x 24 size. Nonetheless, they still have a 3:2 aspect ratio.

4:3

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Photo by Ian Dooley

Cameras with smaller sensors, like those on compact cameras or smartphones, typically use 4:3 aspect ratio. The same format is also used by the aptly-named, micro four-thirds cameras, which have advanced features like DSLRs but are significantly smaller.

1:1

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Photo by Ian Dooley

Also called the square format due to the shape of the image it produces, this aspect ratio is most common among medium format cameras. Just like 3:2, 1:1 also carried over to digital camera from a standard film size. Although rarely used even in digital platforms, it became popular when Instagram adopted it when it first launched in 2012.

16:9

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Photo by Ian Dooley

Due to its considerable width, this format is considered panoramic. In other words, it captures a wider area than other aspect ratios. That’s why it’s the format a lot of landscape photographers prefer. It’s also popular among filmmakers because of the cinematic look it offers. In the late 2000s, it surpassed the 4:3 video format in popularity and is now the standard for television and online content.

03. Why do I need to change my aspect ratio?

Choosing the right aspect ratio when you compose your photos is vital in where it’s going to end up.

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Photo by Georgia de Lotz

If you’re uploading photos on Instagram, for instance, the options you have are relatively limited. Right now, it only allows you to use 1:1 (square), 1.91:1 (horizontal), or 4:5 (vertical), so no matter how well-composed a photo is in 3:2, it might not come out as good once on Instagram.

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Photo by Jonny Caspari

Similarly, you’ll most probably end up still having to crop your photos if you plan on printing them since you’ll have to adjust to the compatible aspect ratio. For instance, a photo with a 3:2 aspect ratio can only be printed in 4x6, 8x12, or 10x15. Meanwhile, a photo with a 4:3 aspect ratio can only be printed in 6x8.  

Knowing how you’re going to use the photo and setting the aspect ratio beforehand will ensure that you can compose it well.

04. Which aspect ratio is the best?

Choosing the aspect ratio to use mainly depends on your camera as well as the type of photographs you want to take. For instance, if you're going to shoot panoramic landscapes, then 16:9 would be ideal. And if you want to upload your images to Instagram, then consider 1:1. For regular photos, then 3:2 or 4:3 would suffice.

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Photo by Pine Watt

When choosing a format, think about the type of camera you have. To maintain quality, the ratio of your image size should never exceed your camera sensor's. For instance, if you’re using a micro four-thirds camera, stick to 4:3 or 1:1. If you try 3:2 or even 16:9, you’ll be forced to crop a considerable portion of your photo. Consequently, you’ll end up with a photo with poor quality.

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Photo by Ty Feague

If you see yourself changing aspect ratios often, then try using a full-frame camera. Because it features a large high-definition sensor, you can crop your photo and still retain its quality. Unlike its smaller counterparts, its ability to capture fine detail gives you more freedom to choose from a wide variety of formats without worrying about noise and grain.

05. How do I adjust my aspect ratio?

Most DSLRs nowadays let you choose the aspect ratio before taking the photo.

Normally, you can choose 3:2, 4:3, 16:9, or 1:1. And if you pick a format other than 3:2, you’ll see a box on your screen which indicates where the rest of the frame gets cut off. So all you have to do is compose your image within that box and ignore everything outside it. When you press the shutter, your device automatically crops it to your specified size.

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Photo by John Webster

Most smartphones also give you the option to change aspect ratios. For instance, iPhone offers square (1:1) and panoramic (16:9) on top of the default photo mode (4:3). When you go to the Photos app, you can also crop your image to any format from square to 9:16 (basically just 16:9 but in portrait orientation). 

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Photo by Yiran Ding

Of course, these functionalities aren’t limited to just iPhones. Almost every other phone has a variation of this feature as well. You can also easily change the aspect ratio of your photos by cropping post-process using your favorite editing suite.

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Photo by rawpixel

When changing your aspect ratio, always remember that different formats affect the composition and the size of your image. That’s why, if you’re shooting for specific platforms such as Instagram, you need to be mindful of how the aspect ratio is going to affect your final product. Train yourself to frame each shot carefully and to think with your aspect ratio in mind.