LESSON 85
Resolution and aspect ratios
Pixel counts and the shape of frame.
IN THIS LESSON
- Resolution is a pixel count
- Aspect ratio is the shape
- How the two fit together
- Practice: choosing for the job
Resolution is a pixel count
In video, resolution usually means the number of pixels across and down, written width by height. Full HD is 1920 by 1080. Ultra HD, often sold as 4K, is 3840 by 2160, exactly twice as wide and twice as tall, so four times the pixels. Cinema counts a little differently: the Digital Cinema Initiatives standard calls 2048 by 1080 2K and 4096 by 2160 4K. Strictly speaking, resolution should mean pixel density, pixels per inch, but the industry uses the word for pixel dimensions and so will we. More pixels give room to crop and stabilise, at the cost of bigger files.
Aspect ratio is the shape
The aspect ratio is width divided by height. Television was 4:3 for most of the twentieth century and is now 16:9, which works out at about 1.78 to 1. Cinemas mostly show either 1.85:1, known as flat, or 2.39:1, known as scope, which is often rounded to 2.40. Stills cameras commonly use 3:2, and social apps made the square 1:1 popular again. When a picture of one shape goes onto a screen of another, it is either cropped, stretched, or given black bars: letterbox bars above and below, or pillarbox bars at the sides.
How the two fit together
A sensor or a recording format has its own native shape, and the final frame can be a different one. A film for 2.39:1 can be shot on a 16:9 sensor and cropped top and bottom, losing some pixels; or it can be shot with an anamorphic lens, which squeezes a wide view onto a narrower sensor and keeps more detail. In a cinema package, a flat 4K picture is 3996 by 2160 and a scope 4K picture is 4096 by 1716, which shows how each shape spends the same container differently.
Practice: choosing for the job
This is working practice. For web and television, record 16:9 at 1920 by 1080 or 3840 by 2160 and you will fit almost every screen. If the piece will also run on phones, frame with a safe middle so a vertical crop still works. For a cinematic look, frame for 2.39:1 by adding guides in the monitor, not by stretching later. Decide the delivery shape before you light, because a wide frame shows more of the set and a tall one shows more ceiling and floor.
| Name | Pixels | Shape |
|---|---|---|
| Full HD | 1920 x 1080 | 16:9 |
| Ultra HD (4K UHD) | 3840 x 2160 | 16:9 |
| DCI 4K container | 4096 x 2160 | about 1.9:1 |
| DCI 4K flat | 3996 x 2160 | 1.85:1 |
| DCI 4K scope | 4096 x 1716 | 2.39:1 |
Try it today
- 01Turn on frame guides for 2.39:1 on your camera or monitor.
- 02Shoot the same scene once for 16:9 and once for the 2.39 guides.
- 03Crop both in your editor and compare what each frame leaves out.
- 04Export a short clip at 1920 by 1080 and one at 3840 by 2160.
- 05Check the file sizes and decide which your next job needs.