this post was submitted on 03 Aug 2023
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I had always used incandescent bulbs in practicals but now there are LED bulbs made specifically for film sets. Household LED bulbs are usually a mess on camera with ugly color spikes and/or flickering.
I've been lighting almost exclusively with LED these days aside from some HMI's, but even those are starting to get LED competition, at least for smaller ones.
Look at the Power Factor (PF) and Colot Reproduction Index (CRI) of the LED light bulb.
If the former is something like 50% then it means it has a cheap power rectifier inside (little more than a bunch of diodes) which doesn't at all filter the power fluctuating nature of AC (basically all it does is make the negative side of the sinusoidal wave that's AC become positve and leaves the whole voltage variance from 0 to max and back untouched) hence the flickering.
The latter quite literally tells you how good the colors look under that lighting. You want at least 90%, with more being better.
Mind you, nowadays CRI is usually not a problem, but the whole cheap power rectification inside the bulb generally is (because a basic power rectifier can cut 10% or more of the manufacturing price of a lightbulb).
Cri is a common specification I see, even if I suspect lots of lying. Where do you find PF information? I don't remember ever seeing it on any bulb packaging before.
Yeah, that's the problem: PF is not mandatory to be in the packaging so it's not usually there.
If you buy online, sometimes you can find it in the product information section.
I've noticed that the "usual chinese sellers" will mention it if it's good (say, 80%) but not when it's the cheap-converter one (50%).
Alternativelly when looking for the bulbs not likely to flicker you might also look for the "dimmable" ones, as the abiloty for a light lamp to support an external dimmer requirex a better power converter inside the bulb.
Thanks for your response! If you light events with broadcast cameras, I am the annoying video engineer behind the camera controls asking about flicker and color balance. I hope they keep making y'all's specialty bulbs. Looks like there's a big list of exceptions!