LEDs are one of the greatest lighting tools a church tech can use. They are flexible units that make our lives easier. However, like any light source, there are some things to overcome to be able to achieve the best finished design.
LEDs are impressive on so many ends. They are relatively simple and require almost no maintenance. LEDs offer an amazing variety of color variations and are incredibly energy efficient, compared to most traditional light sources.
With all the great things LEDs can do, there are also some drawbacks. Let's explore how we can overcome these drawbacks to get the most out of fixtures and serve our churches well.
An unnatural looking skin tone created by an LED light can become a huge distraction.
As we move away from incandescent fixtures to LEDs, one of our primary concerns should be color rendering, which is the measurement of how true an LED portrays a gamut of colors. Many lights are marketed with CRI values, which measure color rendering quality. The higher the value, the more true colors appear under this light.
Our biggest consideration in this area is skin tone. An unnatural looking skin tone can become a huge distraction and even make people subconsciously feel anxious. A light with a low CRI typically looks unnatural, unflattering and fake. Obviously in the church realm, we always want to be authentic and our stages should visually match this.
So does this mean every LED we have should have a high CRI? Not necessarily, the key is to use the right fixture for the right purpose. If you are using (or considering using) LED front lights, those need to have a high CRI. Typically I'd suggest a CRI from 88 to 100 for front lights. More than that though, the light needs to look good to your eye. You should always trust your eye over a spec measurement. If you see imperfections in the color, keep looking for the right set of LED front lights. There are some good LED front light products out now that create a natural feel with a high CRI. The same suggestions go for houselights and sidelights.
Midrange CRI (60-88) products can work well for backlight, and scenic lighting. In those areas, you are typically not directly lighting large areas of skin and it therefore can be much more forgiving.
This quality of light and color rendering becomes even more of a necessity when dealing with video. Cameras are not nearly as sophisticated as our human eye and are not forgiving when it comes to poor light quality and varied color temperature.
While there is a significant amount of science behind CRI, there are also a few better ways to measure true color rendering. If you want to get deeper into this, I suggest listening to the LightingNerds.com podcast, particularly Episode 7 at 12:15. Warning, it gets super nerdy and awesome!
LEDs can also present interesting issues with shadowing. Typical LEDs on the market use multiple sources to create their light output. These multiple sources can create shadows that are less than appealing. Many manufacturers are turning to homogenizing lenses that combine the LEDs into a single source. These are great and go a long way to almost eliminate this issue.
For those like me who already own RGB LEDs, we can do a few simple things to minimize the impact from this. Staying away from a color mixed white when lighting people is a huge help. A color mixed color using only two sets of emitters can complement the look you are already building by introducing colors in the same spectrum. Using diffusion can help as well. Using a blue diffusion filter like Rosco 121, for example, will smooth out a bit of the shadowing and make it less noticeable. Lastly, I try to land my shadows in places that do not create a visual distraction. I keep the shadows away from white set pieces where you can see each color of LEDs. I also try to stay away from side lighting solely with RGB LEDs. It can create shadows across the nose and contours of the face that can be distracting.
LEDs can present some unique challenges with video as well. Our eyes and brains will average out some minor issues with color differences in lighting that cameras cannot. A pure cyan coming from a gelled par can light has a wide spectrum of multiple bandwidths of visible light, where as an RGB LED has two distinct bandwidth areas of visible light that combine to make cyan. Although our eye averages out this color across all bands, many times cameras see more of the narrow wavelength blue and display it over the green.
Also, LEDs operate with different refresh rates, which can create interesting flicker issues that can appear in video. Most LEDs have either a refresh rate of 60 Hz or have an adjustable rate. The biggest key to preventing flicker issues is to make sure the refresh rate on your LEDs and the shutter speed on your camera are wholly divisible. For example an LED at refresh rate of 60 Hz and a video camera with a 30 frames per second shutter rate is divisible down to 2.
This means there would be no flicker presented in the resulting video. A 50 Hz LED and a 30 FPS camera, though, would be divisible down to 1.67, which m would result in one seeing a flicker in the created video, as the refresh and shutter rates would not line up.
Hopefully these few tips are a welcome help to those of you using LEDs in your role!
Steven Hall has served on staff at Journey Church in Norman, Okla., for more than three years. He has been involved in lighting design for 10 years. As the church’s Technical Director, he oversees all aspects of production but is most involved with lighting and scenic design. Steven also recently started a church scenic company, www.modscenes.com. Steven is a graduate of Full Sail University. He lives in Norman, Okla. with his wife, Sara, and son, Dorian. You can reach Steven on Facebook at www.facebook.com/stevenhallav or by email at [email protected]