Banding/Flickering when Filming an LCD Monitor

Hello again folks,

I’m wondering if anyone has had issues pointing a camera at an LCD monitor? It may just be that my LCD monitor is a bit old and not current tech. My monitor was like $1500 when new… 12+ years ago :joy: and is a Dell 2407WFPb. It was a super high quality panel, 1920x1200 and works great to this day. But doesn’t look good in frame on video (Sony a6400, 1080p 30fps).

When I point a camera at my monitor, it shows banding/pulsing/flickering. Is this just a symptom of an old monitor?

This video illustrates the monitor flickering, but the proposed solution doesn’t make sense to me as my monitor under question supports various framerates. I would have thought it would be an older style backlight or something (fluorescent backlit LCD vs newer LED backlit).

Do newer monitors do this at all? Do you all just point a camera at your monitor and it looks ok (assuming exposure ok)? I’m happy to buy a new monitor if that is the proven solution.

Thanks,
Ben

Cameras and monitors need to be running at the same rate. Here in Aus the power is 50 Hertz, but monitors can run at really odd speeds depending on the software running.
You have two options:
Change the camera to match the monitor hertz (broadcast cameras can do this)
or
Change the monitor refresh rate to match the camera (i.e. 50hertz here in Aus)

I hope this helps

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Thanks @TimB!

In North America we use 60hz mains power, and my monitor is set to 60fps. My camera however is set to 30fps. I thought that because 60hz is an even multiple of 30fps we’d be ok. But maybe I’ll try dropping my computer to 30fps…

Also for those trendy YouTubers who advocate 24fps for that “cinematic look”, are they really dropping their monitors to 24 fps? I’m just surprised how hard it was to find any information on this topic. I’d of thought that if every YouTuber had to do this it would have a few dozen videos covering every major platform/OS.

I’ll try dropping my PC to a forced framerate of 30fps, but still interested to hear more people chime in! Especially a few people in a country with 60hz power and 30fps for most live streaming.

The thing is, LCDs do not flicker, at least not in the sense CRTs did. LCD does not blank the screen at the blanking interval, it just refreshes pixels from the last state to the new one.
Any LCD flickering is caused by the backlight, and that may (or may not be) related to the screen refresh rate.
If your screen is older, it’s probably using CCFL backlight, CCFL lamps are high voltage, powered by a voltage inverter that operates on a specific frequency or a set of. It is quite possible your monitor backlight operates on a fixed frequency regardless of screen refresh rate.
Newer monitors have LED backlight (and various dynamic backlight controls) so they possibly sync backlight frequency with refresh rate, that explains the video.
Try changing the camera framerate and shutter speed and you might catch the sync frenquency and reduce flicker.

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Thanks @gimzo, you are right!

I found another video about screen flickering which suggested I increase the screen brightness to 100%. The PWM dimming of the backlight was causing the banding, and changing the backlight brightness to 100% = no dimming/pwm = no flickering/banding.

This worked great for me! 100% brightness is not too bright, especially with a couple video lights on. I normally have it dimmed down for day job software development type work where you just want to be easy on the eyes.

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