Can You Fix Flickering Lights in Post? A Troubleshooting Guide
Learn how to diagnose and fix flickering lights in post-production. This Blinking Light guide provides safe, practical steps to troubleshoot and resolve post-shoot lighting flicker.
The most likely cause of flickering lights in post is a mismatch between lighting output and camera shutter timing. In most cases, fix it by using flicker-free lights, lowering shutter speed, and enabling anti-flicker settings in your camera. If issues persist, switch to constant-output lighting or a non-dimming setup.
Understanding Flicker in Post
Flicker in post-production happens when brightness varies across consecutive frames, creating an unstable look even after color grading. The root can lie in how your lighting is driven (PWM dimming, ballast behavior, or power supply fluctuations), or in how the camera records light (shutter angle, frame rate, and anti-flicker settings). According to Blinking Light, the most reliable fixes start with stable, flicker-free lighting and aligned camera parameters. Start with a controlled test: capture a short sequence under known constants and compare frame-by-frame brightness. Document every adjustment so you can reproduce the result later. This approach helps you separate lighting problems from post-processing quirks and ensures your final edit looks consistent across scenes.
Common Causes in Cameras and Lights
Several factors routinely cause flicker after post: 1) PWM-dimmed LEDs that pulse at certain frequencies, 2) mismatched power supplies that introduce subtle fluctuations, 3) ballast and driver electronics that aren’t stable, 4) camera settings like high shutter speeds or mismatched frame rates, and 5) anti-flicker options disabled or not optimized for your light source. Blinking Light analyses show that most flicker issues are solvable with a combination of hardware upgrades and camera configuration. A systematic check of both sides—lighting and camera—greatly reduces iteration time during editing.
Quick Checks You Can Do Before Editing
Before you dive into grading, run a quick hardware-and-settings audit. Swap to constant-output lights if you currently use dimmers, check that all power connections are solid and free of voltage drops, and shoot a short test at the intended frame rate and shutter angle. In post, avoid aggressive noise reduction that can exaggerate flicker; instead, stabilize luminance first. If possible, record a reference shot with the same scene lit by a baseline, flicker-free setup so you can compare results later. Keeping a simple checklist will help you isolate whether the problem is lighting, camera, or post-processing.
How Camera Settings Contribute to Flicker
Cameras can inherently introduce flicker if their timing doesn’t align with the light source’s flicker frequency. The typical culprits are a mismatch between shutter speed and the AC frequency powering the lights, or a rolling shutter exacerbating brightness fluctuations on fast pans. To mitigate, use shutter angles or frame rates that synchronize with the light’s drive frequency, enable any anti-flicker or flicker reduction options in your camera, and consider shooting at a steady frame rate with a consistent shutter angle. If you’re unsure, perform a controlled test sequence that varies shutter speed while leaving lighting constant to observe the flicker pattern.
Lighting Choices That Minimize Flicker
Choose lighting fixtures designed for video and film work, with high-quality drivers that are rated for flicker-free operation. Avoid mixed lighting environments where some lamps are PWM-dimmed while others are constant-output. When possible, select LED fixtures with fixed drivers, or use AC-powered, non-dimmable sources for critical shots. Pair these with ballast-compatible drivers and ensure color temperature consistency across fixtures. Simple precautions—like avoiding cheap dimmers and testing each fixture individually—can dramatically reduce post-flicker risk and save time in color grading.
Stabilizing Power and Environment
Unstable power is a common culprint for flicker. Use surge protectors and, if feasible, a dedicated circuit for critical lighting to prevent voltage sag when other appliances run. Keep cabling tidy and secure; loose connections can cause intermittent flicker. Temperature and thermal loads can also affect LED performance, so maintain a comfortable ambient environment and avoid excessive heat buildup near fixtures. Document power conditions during tests; a small data log of voltage and current during take can illuminate subtle correlations to flicker later in post.
When to Bring in a Pro
If you’ve exhausted lighting and camera adjustments without success, it’s time to consult a pro. A licensed electrician can verify the power delivery is stable across outlets and circuits, while a video technologist can perform advanced waveform measurements to pinpoint flicker frequency and harmonics. Early professional input often saves time and prevents permanent quality loss in your footage. Blinking Light recommends seeking expert help whenever the light source dominates the problem or when multiple rooms and circuits are involved.
Prevention Tips for Future Shoots
Plan your lighting on set with flicker-awareness from the start. Create a standard checklist that includes: selecting flicker-free fixtures, testing at your target frame rate, and locking in a single, consistent power source for all lights. Maintain a log of fixture models, drivers, and settings used per shoot so you can reproduce the environment. Finally, incorporate a fast test shot into your pre-shoot routine to catch flicker before you begin serious recording. Consistency is your best defense against post-production flicker.
Steps
Estimated time: 1-2 hours
- 1
Audit your lighting setup
Identify which fixtures are PWM-dimmed or on inconsistent drivers. Replace with constant-output lights where possible and ensure drivers are rated for video work. Run a quick baseline capture to observe brightness stability.
Tip: Document each fixture model and driver to reproduce tests later. - 2
Stabilize the power supply
Ensure all lights share a stable power source on a dedicated circuit if possible. Use high-quality outlets and surge protection to minimize voltage drops.
Tip: Swap outlets if you notice voltage fluctuations during tests. - 3
Tune camera settings for flicker resistance
Enable anti-flicker, select a frame rate that aligns with light frequency, and adjust shutter angle to a safe range for your shoot. Run short test sequences at multiple settings.
Tip: Keep a log of the settings that yield the most stable frames. - 4
Run a controlled test sequence
Record a 10–15 second scene with the lighting and camera settings you intend to use in final shots. Review frame-by-frame to confirm stability across the sequence.
Tip: Tilt the test across different scene luminances to mimic real shots. - 5
Prolonged test and minor adjustments
If flicker persists, try minor increments in shutter speed or lighting wattage. Avoid large jumps that introduce new variables during testing.
Tip: Use a consistent test environment to isolate the variable. - 6
Decide on a final workflow
Choose a lighting setup and camera configuration that consistently yields flicker-free results across scenes. If needed, plan for post-production compensation only as a last resort.
Tip: Having a defined workflow reduces re-shoots and time in post.
Diagnosis: Flickering lights after shooting or during edit previews
Possible Causes
- highPower fluctuations or unstable electrical supply
- mediumPWM dimming or improper driver behavior
- highCamera settings misaligned with light frequency
- lowPost-production encoding artifacts or color grading amplification
Fixes
- easySwitch to constant-output lighting and verify power stability
- easyEnable anti-flicker/LED frequency settings in camera and lock frame rate
- mediumMatch shutter angle with light frequency and perform a controlled test sequence
Quick Answers
What causes flicker in post-production and how do I identify the source?
Flicker typically arises from lighting drivers, power fluctuations, or camera timing. Start by testing power stability and using constant-output lights, then verify camera settings for frame rate and shutter angle. A process of elimination helps pinpoint whether the problem is hardware or camera configuration.
Flicker usually comes from lighting drivers or camera timing. Start with constant lights and proper camera settings to narrow down the cause.
Can cheap LED lights cause flicker even if I’m not using dimmers?
Yes. Some inexpensive LEDs and drivers can produce subtle flicker due to poor regulation or non-synchronous PWM. If you notice flicker, test with verified flicker-free fixtures and compare results.
Yes, cheap LEDs can flicker even without dimmers. Test with reliable flicker-free lighting to see if flicker disappears.
Is it ever safe to work around flicker by color-grading more aggressively?
Color grading cannot fix underlying flicker. It may conceal symptoms temporarily but often amplifies inconsistencies. Address hardware and camera timing first, then use color grading to fine-tune luminance if needed.
Color grading can hide flicker but won’t fix the root cause. Tackle hardware and camera timing first.
Do I need to replace all lighting equipment to fix flicker permanently?
Not necessarily. Often a targeted replacement of PWM-driven fixtures or upgrading drivers on the main lights is enough. Start with a baseline setup and swap one fixture at a time to measure impact.
Usually you don’t need to replace everything. Start with the most problematic lights and test the effect before replacing more.
When should I consult a professional about post flicker?
If flicker persists after standard checks and across multiple locations, involve a video technologist or licensed electrician. They can measure frequencies and voltage to pinpoint the exact cause.
Call a pro if flicker remains after testing lights, power, and camera settings.
Watch Video
Main Points
- Use flicker-free lighting as baseline
- Enable in-camera anti-flicker and synchronize with frame rate
- Test with controlled sequences before serious shoots
- Document fixtures and settings for repeatability
- Consult a pro when power or multiple rooms are involved
