What Is An Aspect Ratio
To put it simply, the Aspect Ratio is the size of the width and height of your footage relative to one another. For example, a 16:9 aspect ratio is 16 units wide and 9 units high. The units are not a set size, but rather a relative measurement of width and height.
Of course, the Aspect Ratio should not be confused with the resolution of the picture. Resolution is the actual measurement of the pixels that create the picture, for example, 1920×1080 means the picture is 1920 pixels wide and 1080 pixel high. This 1920×1080 pixel footage can be set into different aspect ratios like 16:9 or 4:3.
4:3 Aspect Ratio
4:3 aspect ratio is one of the older ones and was used by old CRT TVs and Cinema Screens. The reason being the 35mm film back then was made up of square frames so the displays had to be made in relation to the film, hence the squarish 4:3 aspect ratio. Because of that, using a 4:3 aspect ratio when shooting a video can really help when trying to convey the feel of old footage. 4:3 aspect ratio, which is more squared compared to other mainstream aspect ratios, is also good when the focus of your video is mostly vertical rather than horizontal. For example, you are mostly focused on showing a character rather than displaying a big field.
Beside filmmaking, Instagram is the main platform that endorses the use of 4:3 since it is a “Smart Phone Display” focused social media platform which means scrolling down in a portrait style display that is in a reversed aspect ratio, mostly either 9:16 or 9:18. So to fit the video or picture in the display, 4:3 is the best option since it can keep most of what you want to show and get the most out of the display form factor.
1.85:1 and 2.35:1 Aspect Ratio
4:3 was used because of the limitations of the film reels that were available but in the real world, human eyes see things in a wider aspect ratio. So the cinematographers of the time began experimenting with ways to widen their field of view while still using the available 35mm reels they had and as a result of that, Anamorphic lenses were born. What Anamorphic lenses do is that they squish the scene from the sides so that it can fit onto a 4:3 film and then later on for the screening, the reverse is done and the result is a wide image that has a lot more in it and is also more pleasing to the viewer.
1.85:1 and 2.35:1 are still the most common aspect ratios used by cinematographers. So every time a filmmaker wants to create a “Cinema Feel” for its film, they are going to use these aspect ratios even if they have no intention of screening them in a cinema.
16:9 Aspect Ratio
Hands down the most common aspect ratio is 16:9 which is used by all modern devices like TVs and Monitors. Smartphones also have been 16:9 for quite a while but in recent years they are shifting to other aspect ratios like 18:9 and even 21:9 which is Cinema Aspect Ratio. Also, almost all the video content you will find on the internet, like on youtube, is 16:9. But why is 16:9 so popular? Well, when introduced, 16:9 was the best middle ground between 4:3 and widescreen. A 16:9 display can easily and without any loss display both other ranges of aspect ratios with black bars either on the sides or on the top and bottom. But what is kind of interesting is that 16:9 which was mainly created as a platform for other dominant aspect ratios is now that dominant one out there.
Where To Use Different Aspect Ratios?
Using different aspect ratios is something more than just for displaying the content on a compatible device. Aspect Ratios, if used cleverly, can be a tool to guide the viewer toward a certain message or the general feel of a setting. For example, non-widescreen aspect ratios like 4:3 or 1:1, which is a complete square, are great when you want to create and convey a claustrophobic feeling. This can show that maybe your character is stressed. Or as I mentioned before, squared aspect ratios also create the feel of an older video. And since we are programmed unconsciously to regard widescreens to the “unreal” world of cinema, 4:3 feels more personal and they can work great for memory sequences.
But still, all these are subjective and can be used based on the decision you as a creator make. Maybe you decide to categorize your story into different parts and to subconsciously tell your viewer that we are in which section of the story, you dedicate an aspect ratio to that section. For example, present-day can be in 16:9 and flashbacks are 4:3 and now your viewer will immediately and subconsciously know which is which and what to expect. But you need to be very careful and consistent because any inconsistency with these rules you have set can create chaos in your storytelling.