Before we begin to talk about color temperature, we should begin with a quick review of how is light measured. The most basic unit of light measurement is the lumen. There is a common misconception that light output is measured in watts, however this is not accurate. Watts are the measurement of electrical energy that certain type of lamp will consume. The actual light output is measured in lumens. One lumen is equal to the amount of light from one candle at a distance of one foot. For you theatre folk, here is where we could branch out into footcandle history...but I digress. So ok, now we know what a lumen is. Why? Well, as we progress away from incandescent lighting fixtures the old way of using watts to describe output will be dated. When we, as lighting professionals, are looking to purchase or rent lighting fixtures for specific jobs - we are looking at the lumens of the fixture. We could care less how much power it will take to operate the fixture, we'll figure that out later - we want to know how "powerful" (in terms of the output) that lighting fixture will be at what distances.
Ok, by now you are thinking...well, what about color temperature? Color temperature is not easily explained, partially because the first thing you have to understand is that "white" light does not exist. Alright let's go way back, back to our Roy G Biv days. Everyone knows this 'scale' of the spectrum. Well, this also can pretty much explain color temperature. Color temperature is measured in degrees of kelvin. The lower the number of kelvin the warmer, or more red, the light will look. The higher the number of kelvin the cooler, or more blue, the light will look. So think of 2500k-3000k range of being a "typical" household lamp with the burnt red to yellowish tint. Then up to around 3500k we are into bright, almost "white" yellow. On up the scale to 4000k for a "bluish" light. Then we get into daylight, which is the 5000k-7000k range. We will save the next portion about CRI - which is how your eyeball actually sees light for the next level of blog post!
How does all of this physics translate in to the special event lighting world? Well, hopefully it is obvious by now that just "throwing light around the room until it looks cool" is not how any job should be approached. Lighting design is not only an art but it is a careful calculation of not only what we have just scratched the surface about here but also a slew of technical mumbo jumbo. Don't worry, we take total care of the mumbo jumbo to the point where you don't even know the mumbo jumbo had to happen in the first place!
Below is a picture of us replacing some lamps in an auditorium. I quickly snapped this photo with my phone of two of the chandeliers in the space. Notice the difference in color temperature? A good lighting designer will know which one is appropriate for the job...which is why we were called in! Let us keep your event at the right temperature! ~Beth Reyes, Lead Technician Solus Lighting LTD