Slow motion is a classic cinematographic technique that lends an air of fantastical surrealism to a scene in your video. This style of shooting gives the viewer the ability to see the details of time progression, which emphasizes a particular moment.
Slow-motion video can be achieved through most consumer cameras; although, there are a few nuances that you must be aware of before you start filming. Here is a breakdown of slow-motion basics, shooting methods and post production tips:
Slow motion captures many pictures in a very short time frame, ranging from 120 frames per second (fps) to upward of 300 fps. The video projection of captured images plays back at 24 to 30 fps. If 300 images were filmed in one second, then projected at 30 fps, the video will last for 10 seconds on the screen. Alternatively, real-time video is shot at approximately 24 fps and projected at 24 fps. If you slowed down the 24 fps clip, the image would be blurred since there is no image data to fill the gaps between images. Peta Pixel has a slow motion comparison video that provides examples of the variation between frame rates.
A rule of thumb when you shoot slow motion video is to use a lot of light. When you take photos quickly, there is less opportunity to properly exposure your image. Inadequate lighting makes your images appear dark and dull. Indoor slow motion can be difficult to achieve unless you have artificial light, such as a continuous studio LED light. Nighttime slow motion video is rarely achievable because the light source is not adequate. Aim to shoot your video within the golden hour when the sun is closest to the horizon in the early morning or late afternoon.
To capture a good slow-motion video, you need to choose the proper frame rate for your subject. There are specific frame rates that suit certain situations better than others. Here are just a few examples:
- 120 fps: This speed measures about a quarter speed of real time. 120 fps is ideal for sport replays.
- 300 fps: This speed is generally used to show slow-motion walking or love scenes.
- 600 fps: This speed is ideal for a more fantastical shot of human or animal movement.
- 1,000–1,200 fps: This rate is ideal for explosions. Human and animal movement is too slow for this rate.
- 5,000–10,000 fps: This frame rate is perfect for capturing flying bullets, glass explosions or intricate pyrotechnic explosions.
Before you edit your video, ensure your editing program can upload your footage at the desired frame rate because some may automatically convert your uploaded footage to a 24 or 30 fps. Make sure you are working with a project frame rate rather than an actual frame rate.
You may need to adjust your playback speed, which can be altered by percentage increments. Use your ability to manipulate speed throughout your keyframes between 100 percent and 25 percent to progressively slow their rate of projection. Many action films use this technique of speed ramping for emphasis on human movement.