ShutterFinder — Flicker Detect

Stop guessing your shutter speed on set. ShutterFinder detects light flicker instantly and tells you the exact shutter speed to eliminate it.

HOW IT WORKS
Point your iPhone at any flickering light source — LED panels, fluorescent tubes, HMI lights, monitors, practicals — and tap MEASURE. ShutterFinder uses your iPhone's 240fps high-speed camera and real-time FFT analysis to detect the precise flicker frequency. Within seconds, you get the optimal shutter speed to shoot flicker-free.

BUILT FOR FILM PROFESSIONALS
• Detects flicker frequency with precision using FFT spectral analysis
• Recommends the exact shutter speed in time (1/50) or shutter angle (180°) — switch with one tap
• Supports all common shooting frame rates: 23.98, 24, 25, 29.97, 30, 50, 60 fps — plus custom input
• Change shooting frame rate after measurement and see shutter recommendation update instantly
• Works with any flickering source: LED, fluorescent, HMI, neon, monitors, practicals
• Identifies the source type (50Hz mains, 60Hz mains, PWM LED, etc.)

ONE-TAP WORKFLOW
No complicated menus or settings. Point at the source, tap MEASURE, get your shutter speed. That's it. The app automatically stops measuring when it has a confident reading.

TECHNICAL DETAILS
• Uses 240fps slow-motion capture for high-resolution temporal sampling
• FFT (Fast Fourier Transform) analysis via Apple's Accelerate framework
• Sub-Hz frequency accuracy with parabolic interpolation
• Automatic exposure adjustment for difficult lighting conditions
• Detection range: 40–500 Hz

Requires iPhone XS or later with iOS 17.0+.