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this post was submitted on 17 Aug 2024
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Asklemmy
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LED lights are either all on or all off, the only way to dim a LED, is to make it blink really fast and change the time it’s on vs the time it’s off. Cheap LED lights don’t blink fast enough, so you see them flicker.
That's not the only way to dim an LED, just the cheapest. Variable current power regulators are the premium option.
A screw-in LED bulb combines LEDs and power regulating electronics. Some of them handle the variable input voltage a household dimmer provides gracefully, but that's more expensive.
Changing the current can change the hue (color) of the led. In some cases it’s okay in some cases it isn’t. Cinema lights for instance don’t dim with voltage because of that. Instead they have 3 separate drivers synchronized to dim in a canon. One after the other so that there is always the same number of LEDs on at all time regardless of the dimmer level.
Hi Lazaro!
That’s not always true, actually. For example, Digital Sputnik lights (and some LED tape that I have that I use my current control dimmers on) utilize current control dimming. This alternative type of dimming allows them to work even with super high speed frame-rates due to having very little or even no perceivable flicker. It’s certainly unpopular in comparison to PWM but definitely not unheard of in the film industry.
I used to use the technique you mention with >2K tungsten lights for footage above 1000 fps. I figured out (in the absence of a budget that could afford a DC rectifier) that if I ran the same amount of lights on each of the legs of a 3 phase Delta style Gennie that they would effectively fill in each others’ pulses. I further enhanced that effect by shining all 6 5K’s (for example) on the same rag.
I used that technique here: https://youtu.be/w9-NoEnWSgk
That’s awesome! I love how deep we are going with this! I have to admit I don’t k or as much about cinema lighting as I know about cameras and Steadicam.
I’m happy to share any experiences I have had as we’re likely the only two filmmakers in the whole fediverse right now!
:)
That's true. Describing current regulation as the premium option was an oversimplification. For household lighting, it's usually the premium option.