Put simply, aspect ratio refers to the shape of the image being projected. Almost all projections today are in the shape of a rectangle, but exactly how wide or narrow is determined by the aspect ratio.
Choosing the aspect ratio of your screen can be very confusing because the screen, projector and video source can all be different and both the projector and video source can usually be zoomed or scaled to change aspect ratios. An image with an aspect ratio of 4:3, for example, means the width of the image is 4/3 or 1.33 times the height of the image. An image with an aspect ratio of 16:9 means the image is 16/9 or 1.78 times the height. In our opinion, though, the most important thing to consider is the native aspect ratio of your projector followed by the aspect ratio of the images you will most commonly be projecting. It is best to match the native aspect ratio of the projector to that of the screen so the image fills the entire screen. But if the ratio on your projector is adjustable, pick the ratio that will match the majority of your viewing/content. The 16:9 is the most common. Additionally an aspect ratio of 16:9 can accommodate both the 4:3 and 2.35:1 with the least amount of masking (black letterbox style bars).
- 4:3– While there are, technically, many different aspect ratios used around the world for different video formats; the most common are 4:3, 16:9, and 2.39:1. The most common used to be 4:3 (think of old CRT television sets). You will also still find projectors, usually marketed for office applications have a 4:3 aspect ratios. Standard definition television, "standard format" DVDs and most other devices connect with analog composite cables (think yellow/red/white RCA cables) and will output video in a 4:3 format. If you use any of those consider a 4:3 aspect ratio screen.
(4:3) Projector Resolutions: 800x600 and 1024x768
- 16:9– Conversely, most new home theater projectors have a native resolution with a 16:9 aspect ratio. HDTV, Blu-ray and most other devices, connecting via HDMI or other digital video cable, output video in a 16:9 format. An appropriate choice for a screen in those situations would have a 16:9 aspect ratio.
(16:9) HD Projector Resolutions: 1280x720, 1920x1080 and UltraHD 3840x2160
- 2.35:1, 2.39:1– Even with a 16:9 projector and a 16:9 video output the image may still have black bars and won't use the full height of the screen. This is often referred to as letterboxing or cinemascope and often occurs on movie releases where the producers of the media choose to keep the original cinematic aspect ratio and fill the rest of the image with black. Because of this, some people choose to build screens at wider aspect ratios (2.39:1 being the most common) so they can fill the screen with the wider image. Often this just means using the projector to zoom out so the black bars are off the screen (some projectors have a built-in memory to switch between zoom levels).