Explanation of Aspect Ratios for Filmmakers

Although most HD cameras shoot 16:9 natively, we’re going to discuss why 16:9 should be the standard you film with and deliver as a beginner filmmaker or videographer.

Frank Romano III December 12, 2012

There are many different aspect ratios for video and film.

What are aspect ratios?

An aspect ratio is the proportional relationship between an image’s width and height. It’s usually described as two numbers separated by a colon (16:9, 2.39:1, 4:3, etc.). The first number represents the width and the second represents the height. If someone describes the aspect ratio of an image as 16:9 (read as sixteen-nine or sixteen by nine), they mean that it’s 16 units wide and 9 units high. The image can be any size, but the ratio remains the same.

Although you might be unfamiliar with aspect ratios, you’ve probably realized that TVs used to be more square (4:3) and now TVs are widescreen (16:9). When DVDs first hit the market, they were available in “Fullscreen” and “Widescreen” to accommodate the transition from 4:3 TVs to 16:9 TVs. Now, all modern TVs are widescreen. But the term “widescreen” encompasses many different aspect ratios.

4-by-3 and 16-by-9 aspect ratios

Why are there so many aspect ratios?

The evolution of media over time has resulted in many different aspect ratios. The universal ratio for 35 mm film was 1.33:1 (known as 4:3 in video, the motion picture industry assigns a 1 as the height). This changed in the late 1920’s with the onset of sound. To make room for the optical soundtrack, which ran along the side of the film, the aspect ratio was changed to 1.375.1 (slightly wider). 1.375:1 is achieved by cropping the image when projected by adjusting the size of the projector aperture plate. This is known as the “Academy Ratio” because it was created by the Academy of Motion Picture Arts and Sciences. The difference between 1.33:1 and 1.375:1 is negligible. Both are commonly referred to as 4:3.

In the 1950s, televisions came about and adopted the 4:3 format. This was a major threat to the motion picture industry and their way of motivating audiences to return to the theater was by adopting widescreen formats. During this period, many different widescreen aspect ratios and technologies competed for dominance. Some even opted for ultra-wide formats, like Ben-Hur‘s ratio of 2.76:1, or How the West Was Won‘s “Cinerama” ratio of 2.89.1; which utilized 3 cameras filming simultaneously.

2.89 and 1.33 aspect ratios

Eventually two widescreen ratios became the standard for theatrical exhibition: 1.85:1 and 2.35:1. 1.85:1 is very close to 16:9, which is 1.78:1 in motion picture terms. Films made with today’s digital cameras, which film natively in 16:9, are cropped slightly to 1.85:1 for theatrical release. This ratio is the most ideal for today’s TV screens and computer monitors, which are mostly 16:9. Additionally, 16:9 has become the standard for HD formats and television productions. 2.35:1, on the other hand, is much wider and generally considered more cinematic because it’s primary use is theatrical exhibition. Since 1970, the ratio is actually 2.39:1, often rounded to 2.40:1. However many still refer to it as 2.35:1, which creates confusion.

2.35 and 1.85 aspect ratios

Why you should only film in and deliver 16:9 (1.77:1)

16:9 is the standard for HDTV, which means that most households have TVs with an aspect ratio of 16:9. Additionally, video sharing websites like YouTube and Vimeo stream all their content in 16:9. In the past few years, 16:9 has also become a common ratio for computer screens. Long story short, most people view content on 16:9 screens because most content is 16:9. Unless you’re producing something for theatrical distribution, there’s no reason to produce at a different aspect ratio.

Filming at 1.33:1 or 2.40:1 will result in pillarboxing or letterboxing, which means your content will be matted to fit within the 16:9 frame. This is how major motion pictures are presented on home video. If you’re not producing something for Hollywood, the only reason to film in or deliver a different aspect ratio would be for artistic purposes, which can come off as both self-indulgent and pretentious.

Letterboxing and pillarboxing

You are probably already filming in 16:9

If you’re filming with an HD camcorder or DSLR, you’re filming in 16:9. If you’re filming with a standard definition camcorder, you’re filming in either 4:3 or anamorphic widescreen 16:9. In standard definition format, a 16:9 aspect ratio is achieved through a process called anamorphic widescreen, which uses non-square pixels to squeeze the image horizontally to fit in a 4:3 frame. Then, compatible equipment, such as a DVD player, will stretch the image back out. If you’re using an SD camcorder, make sure to film in 16:9 rather than 4:3.

The only way to achieve aspect ratios wider than 16:9 is either through expensive anamorphic lenses designed for motion picture cameras or by matting a 16:9 video. Both methods are unnecessary unless you’re producing something for theatrical exhibition, which you likely aren’t.

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