02/17/2016
Why are my RADION LED Lights so blue?
I have been getting a lot of questions pertaining to the color of the lighting provided by our RADION LED Lighting Systems. The answer is relatively simple if you understand the nature of illumination underwater. It is not the same as illumination in-air.
The RADION LED Lights have a color temperature around 6,500K (Kelvin). This temperature is considered a “full spectrum” light. The problem is not the light source, but rather the distance the light is traveling to illuminate.
We proved 15 feet of poles to lower the light into the water. As you can see in the information below, at 15 feet, you have lost your reds. This means that observing from above the light what you see has no reflection of red. The object you are trying to view is even further away, say another 15 feet. Well, there went your oranges and some of your yellows. What you are left with is your greens and your blues. This is the reason your water will appear blue.
Another advantage of the RADION LED Lights is that they illuminate very well underwater, even if the color you see is blue. One RADION-6 will replace three 1,000 watt HPS lights, which give off a yellow light. Since it is a yellow light you need more to illuminate the same area because yellow does not travel as far as blue.
Is it possible for us to make our lights a warmer color? Of course it is, but you will end up needing more lights to get the same illumination. Just because we can do it does not mean it is a good idea… even if we would sell more lights. We strive to provide our customers with the best value and customer service for their expenditures.
Don't forget to add in the horizontal distance. If you are 10ft underwater, and you are viewing an object 10ft away, the light has actually traveled 20ft, and all of the reds will be filtered out.
The picture below on the left is of our RADION LED Light at Columbia Station
The picture below on the right is of our RADION LED Light at Quad Cities Station
Fundamentals of Underwater Lighting
and Color Temperature
Loss of color underwater at depth
What color disappears first underwater?
Water absorbs different wavelengths of light to different degrees. The longest wavelengths, with the lowest energy, are absorbed first. Red is the first to be absorbed, followed by orange & yellow. The colors disappear underwater in the same order as they appear in the color spectrum. Even water at 5ft depth will have a noticeable loss of red.
At what depth underwater does color disappear?
• Red - 15ft
• orange - 25ft
• Yellow - 35-45ft
• Green - 70-75ft
Don't forget to add in the horizontal distance. If you are 10ft underwater, and you are viewing an object 10ft away, the light has actually traveled 20ft, and all of the reds will be filtered out.
Likewise, you are using a camera and you light up an object 5ft away, the light has to travel 5ft to the object, and 5ft back to your lens, for a total of 10ft, with a significant loss of reds. This is why you always need to get close to your subject to maintain the best color.
Magnification of Objects Underwater
Since we are talking about water, I should note that objects can appear up to 25% closer underwater than they actually are.
Objects will also appear to be up to 33% larger than they are. This is due to the fact that the index of refraction of water is greater than air. This happens behind flat surfaces, such as an underwater camera. It does not happen when using a dome port.
Color Temperature
Light is often referred to having a certain color temperature. Strangely, warm light is a lower color temp, and cool light, blue, is a higher color temp.
Here are some temps of some common light sources
10000-12000 blue sky
6500-8000 shade
6000 cloudy day
5500 inon strobes, S&S strobes, sunlight, flash mode
5000 S&S strobes with diffusers
4800 Ikelite Ds-125, DS-160 strobes
3200-38000 tungsten light
2500-3000 sunrise, sunset
2000 red light
1500-1800 candle
• Increasing the color temp of a photo (called warming it up) brings out yellow, oranges
• Decreasing the color temp of a photo (called cooling it down) brings out blues
