The folks over at FilmmakerIQ are back with an in-depth discussion of working with LEDS, with a special focus on DIY builds—useful things to know as LEDs increasingly take over the world of film lighting. We've posted a few key takeaways below the video.
1. LEDs emit very tight spikes of wavelengths
LED lights are known for being very effiicient, giving out a lot of light power without using much electricity. This is at least partially because they don't waste much electricity generating non-visible elements. No infra-red light, no excess heat, just purely a very tight band of wavelengths. A red LED emits photons from around 610-760 nanometers, and that's it.
The drawback to this is that it's not a very fluid spectrum. Those wasteful units like a tungsten light that emit a ton of extra infrared you don't need have a smooth band of wavelengths, which LEDs don't have without tremendous extra engineering. LEDs create white light via using multiple sources all together, with red LEDs, green LEDs, and blue LEDs working in concert to create balanced color.
2. LEDs are natively DC powered
LEDs are driven natively by direct current, rather than alternating current. In fact, you need to use an LED driver to even use an LED light. This makes LED devices ideal lights to use with battery systems, which also deliver DC current, since they need no conversion to light up via DC. In fact, as demonstrated in the video, you could hold a tiny LED against a button battery and it'll light up.
Credit: Filmmaker IQ
3. Some LEDs cheat to make white
In an ideal world, we would get white for our LED through a complete spectrum light that has LED chips emitting all wavelengths. However, some LEDs just use blue chips combined with a phosphor reflection, a trick borrowed from fluorescent lights. These units might advertise themselves as white, but aren't likely to give you the broad, though segmented, spectrum you get from a multi-source LED.
4. SuperBrite LEDs get hot
One urban legend about LEDs is that they don't get hot, but the SuperBrite LED chips we often see used in film units do generate a ton of heat. They can melt the solder used to hold them on their circuit, and they need cooling on set to keep them serene, which is one of the reasons these units practically always have fans.
The video has a lot of creative ideas for how to integrate practical LED effects into your scene that are well worth a look.