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Slow motion can add drama, detail, and emotion to your footage—but only if it’s done right. One of the most important factors when filming in slow motion is choosing the correct frame rate (FPS). This ensures your footage looks smooth and cinematic when slowed down in post. YouTube Video
What FPS Means for Slow Motion
Frames per second (FPS) refers to how many frames your camera captures every second. A standard video typically plays back at 24, 25, or 30 FPS. When you film at a higher FPS and play it back at a normal speed, time appears to slow down.
The Math Behind It
To calculate your slow-motion percentage, divide your playback FPS by your recording FPS:
Slow Motion % = (Playback FPS / Recording FPS) × 100
For example:
Filmed at 60 FPS, played at 24 FPS→ (24 / 60) × 100 = 40% speed (60% slower)
Filmed at 120 FPS, played at 30 FPS→ (30 / 120) × 100 = 25% speed (75% slower)
Recommended Slow Motion Speeds
60 FPS → 40% speed at 24 FPS playback
120 FPS → 20% speed at 24 FPS playback
240 FPS → 10% speed at 24 FPS playback
Pro Tips
Use higher FPS for faster action (sports, water, dancing).
Maintain proper shutter speed (typically double your frame rate).
Light your scene well, since higher frame rates need more light.
Slow motion can transform ordinary moments into something extraordinary—but only if you respect the math. Plan your FPS based on how slow you want the action and match your settings accordingly.
Using Optical Flow to Achieve Smooth Slow Motion in DaVinci Resolve
When working with 24fps footage, slowing it down can sometimes result in choppy or stuttery playback. But don’t worry, DaVinci Resolve has a powerful tool to help: Optical Flow. This technique smooths out your slow-motion clips by creating intermediate frames, making your footage look seamless, even when it’s slowed down significantly.
Why Use Optical Flow?
Simply slowing down footage can lead to noticeable jumps between frames, especially when you’re working with lower frame rates like 24fps. Optical Flow analyzes the motion in your video and generates new frames between the existing ones, smoothing the transition and creating that buttery-smooth effect.
How to Use Optical Flow in DaVinci Resolve
Import Your 24fps Footage: Start by adding your clip to the timeline.
Enable Speed Change: Right-click your clip, select "Retime Controls", and slow it down to your desired speed.
Activate Optical Flow: Go to the Inspector panel, find the Retime and Scaling section, and set Motion Estimation to Optical Flow. Then, change Retime Process to Enhanced Better for the best results.
Fine-Tune Your Clip: Play back the footage to ensure it’s smooth. You can adjust the retime speed or tweak settings for even better results.
Pro Tip
For best results, use higher frame rates when filming in the first place. The more frames you have to work with, the smoother the final slow-motion footage will be. But even with 24fps footage, Optical Flow can help you achieve fantastic results!
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