Will LED's flicker when shooting at 24 fps on film?

[Will Jacobs]

I'm determining whether or not I could make an LED light bank for a project out of these shop lights: 

https://www.amazon.com/Barrina-8500LM-Daylight-Output-Linkable/dp/B07Q49DNGS/ref=sr_1_8?dchild=1&keywords=led%2Bshop%2Blight%2B5000k&qid=1587769697&sr=8-8&th=1

When shooting with 16mm film at 24 fps at 60 Hz, will there be any flickering? Even if I utilize typical LED video lights?
 

[Will Jacobs]

It appears that flickering will not be an issue after viewing this video: 

 

[Phil Rhodes]

It depends entirely on the specific type of shop light you get, and how those specific lights were designed.

It's true that domestic LED lighting is getting steadily better and better; some of it could be used quite effectively. You have two concerns (other than brightness and directionality, depending on what you're trying to achieve.) The very lowest cost stuff, which frankly might include some work lights, may flicker at mains frequency or at some other frequency based on the designer's whim. Also, the colour performance may be a bit off, and the danger with this is that it may look okay on some things - even skin tones - and then give you a nasty surprise on some other subject, later on. This is the aspect that has really improved recently - it's now possible to get domestic lighting with reasonable colour performance - but the majority of it is still pretty bad.

You can only really determine either of these things by testing on colour charts, with various real-world colours, and at various frame rates. Try it. In the worst case you'll end up with a light that you can use to create cool blue moon backlights for night shoots. A minority of lights may flicker or produce banding on rolling shutter artifacts at any useful frame rate, but that's fairly rare.

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[Will Jacobs]

Phil,

I recently tested the lights with my digital camera and noticed barring at 24 fps. I have since returned them. It was enough to have me avoid finding cheap alternatives altogether and invest in what works and lasts. Thank you for your insightful response!

[David Mullen ASC]

If it's like a 60Hz roll bar, then try shooting at 1/60th.

[Carl Craver]

Hi, I've written an iPhone app that can measure light frequency directly called FlickerFinder. Essentially you point the phone towards the light, it will autoexpose to reveal and measure the flicker, then give you a suggested shutter speed. It's in the final stages, I just need some help calibrating the rest of the iPhones. https://flickerfinder.com

Alternatively if you know the frequency you can use a calculator app https://apps.apple.com/app/id1514983816

I hope it helps, I can answer any questions.

[Tanul Dilwali]

On 5/5/2020 at 9:17 PM, David Mullen ASC said:

If it's like a 60Hz roll bar, then try shooting at 1/60th.

absolutely - in other words, changing the shutter angle to eliminate the roll bar, and re-expose accordingly.

Of course, in a shop, various lights may have different operating frequencies and you may see flickers and banding across a huge range of speeds 

Edited September 24, 2020 by Tanul Dilwali
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