Flicker-Free Shutter Speed Checker

Why Does Flicker Happen?

Most artificial lights — fluorescent, LED, HMI — pulse at twice the mains frequency: 100× per second in Europe (50 Hz) and 120× per second in the USA (60 Hz). A camera exposing a frame during a darker or brighter pulse captures uneven brightness, resulting in flickering banding.

The Fix: Sync Your Shutter

When each frame's exposure time is an exact multiple of the light cycle, the camera always averages the same brightness. For 50 Hz: safe shutters are 1/25, 1/50, 1/100. For 60 Hz: 1/30, 1/60, 1/120.

The Shutter Angle Constraint

Shutter time can never exceed one full frame (360°). As FPS rises, slower safe shutters drop out. At 120 fps with 50 Hz, even 1/100 s (10 ms) is longer than one frame (8.3 ms) — no standard safe shutter exists. Use a flicker-free LED source instead.

Practical Tips

Europe / Asia / Australia: shoot 25 or 50 fps, use 1/50 or 1/100.
USA / Canada: shoot 30 or 60 fps, use 1/60 or 1/120.
Cinema (24 fps) in 50 Hz countries: 1/50 gives 172.8° — close to 180° and flicker-free.
LED / HMI: check if a flicker-free (high-frequency) mode is available.

Modern LED and High-Frequency Drivers

Many current LED fixtures — especially daylight-balanced panels and bi-colour units used in studio and location work — operate at very high frequencies (1000–50 000 Hz) to eliminate flicker at any shutter speed. These are typically labelled "flicker-free" or "high-speed compatible". However, budget fixtures and LED globes in practical lamps still often pulse at mains frequency. Always test with your actual camera at the target shutter speed and frame rate before committing to a lighting setup, especially for high-frame-rate overcranking or variable-shutter creative work.

Fixing Flicker in Post — Can It Be Done?

Flicker introduced at capture is very difficult to remove cleanly in post. Tools like DaVinci Resolve's Deflicker effect and Adobe Premiere's Flicker Free plugin can reduce mild brightness variation, but they cannot restore motion detail lost in underexposed frames of a cycle. For heavy flicker — such as partial frames showing banding from pulsing HMI ballasts — the fix is usually a reshoot. The safest approach is always to verify shutter sync on set using this checker before rolling, rather than hoping to correct it in the grade.