A not so long time ago in the galaxy of which you live in, the entertainment lighting world was dominated by two types of light sources – halogen and arc-source lamps.
These two types of sources were used for broad range of lighting fixtures and for the majority of the industry; our fixtures were defined by the light source that was in them.  Almost all moving head fixtures were lamped with arc-source lamps, and static wash lights were lamped with halogen lamps. There were some exceptions to this rule, especially in film and television, but for our discussion today, we are going to leave it as arc-source for movers, and halogen for statics. This further helped us define our lights for specification. For example, we knew that a 750W Ellipsoidal was perfect for onstage and front of house lighting situations for theatre and that a 250W moving head spot was the ideal nightclub fixture based on its 250W arc-source lamp. We also knew exactly what the quality of white light was going to come out of these fixtures.
Halogen lamps are always warm in color temperature. For example, the most popular lamp in the 750W Ellipsoidal range is the HPL 750W lamp.

 

It comes from a variety of manufacturers, but the spec is pretty much the same. It has a CRI of 100 and a color temperature of 3250K. The HPL 575 lamp is also pretty common. The color temperature is a little warmer at 3050K, and the CRI is still 100. The typical range of Halogen lamps is between 2800K and 3200K.

Arc Source lamps are always cooler in color. Usually ranging from 5600K up to 8000K, these lamps are used in moving head fixtures because of their ability to create a lot of light in a small space and have a good working distance to allow for a bunch of effects to be installed in the fixture. A good example is the 250W MSR lamp. Coming in at 6000K and having a CRI of 90, this lamp was extremely popular in moving heads in night clubs. The cooler color temperature made the apparent brightness of the fixture higher and the high CRI allowed objects being lit to appear vibrantly colored. We still use arc source lamps in most beam fixtures, as well as higher powered spot fixtures. Both Philips with their R series and Osram with their Sirius lamps are providing lower powered and higher output lamps that continue to brighten our stages.

 

 

So, what does this have to do with the color of white and how we use it in today’s world? We still have the options provided by halogen and arc-sourced lamps, but now we have more options and it’s all about choice. With the addition of high power white LEDs, we have more and more flexibility in the range of color temperatures that white LEDs are available in. Also, with the fact that we can combine these LEDs together in one light engine, it gives us the ability to create the ultimate hybrid of white – variable white. Variable white is great because now we do not need multiple fixtures to range our color temperatures on stages. Because of this, we can lower our fixture count and create the exact color temperature that we are looking for. No longer are we trapped at 2800K, 3200K, or 5600K, we can now dial in at 4000K by adding or subtracting the amount of output produced by either the warm or cool LEDs. Beyond white LEDs, we also have color mixing LEDs with Red, Green, Blue, Amber, White and Lime colors on board. This means that you not only have the ability to mix amazing colors, but have the ability to achieve a wider range of color temperatures with a higher CRI than ever before with LEDs. Because of this, our stages have never looked as vibrant and alive as they do right now. By using a combination of all of these sources, we can create any look and color we desire. We can even create plaid if we want to.
But let’s get back to white. Why with all of these colors out there do we always come back to white? It is because that is what our eyes really want to see. Our eyes are not designed to be saturated in one particular color, but to see the entire spectrum. So, picture this….you are standing on a hilltop in the countryside of Western NY in the early fall. You can look down onto an apple orchard.

Your eye is designed to pick out greens, but is sensitive to the red contrast that the apples produce. Or even better, picture the leaves changing colors with all of the warm amber, oranges and reds.

 

This works because the sun produces white light and the colors you see are the result of full spectrum light being absorbed, reflected, and refracted off the orchard rather than a limited color wavelength being projected onto the same scene. If we had the same above scene with a single color, like blue, you would not see all of the contrasting colors. You would only see different shades of blue and black, which would not look that great at all. Your eyes want to see the natural contrast of colors created by the natural light. This is why white light is still important, even with all of these color projecting fixtures out there, we still need white light. In fact, our brains crave it. Single color light, over time, can be exhausting to our eyes. Saturate colors have their place, but white light is extremely important to your show.

 

I have noticed a trend recently in adding in warm white back into live performances. Not with halogen lamps, but with LEDs. Halogen lamps create heat and require outboard dimming. LEDs create much less heat and don’t require as much back end support. As the efficiency of warm white LEDs increases, the more and more I expect to see this trend increase. Warm whites are perfect for lighting people and creating candle light type moods. They also make excellent blinders and have a nice warm glow.

 

Cool white LEDs have been around for a lot longer in the entertainment world. They have been used in moving head spots for years now and have more recently been finding their way onto larger tours which used to be primarily arc-source fixtures. Cooler whites are commonly used for spotlighting people in performances to help them to stand out from the rest of the stage. They are also great for projecting gobos in haze and fog to create aerial effects and cut through the rest of the lights on stage to highlight something specific on stage.
However you choose to create your white light, make sure that your intentions are clear. Remember that natural sunlight is around 5800K and moonlight is around 4000K. HOWEVER, often when we light stages, we tend to make sunlight warmer (around 3200K to 4000K) and night time cooler (around 6000K to 8000K) as this is a convention of theatre.  There are scales out there that can help you dial in the right color temperature for your needs. An example is the one below:

 

 

As we always say, the best way to find out which white works best for you is to experiment with different color temperature combinations.