To see or not to see... That is the question...
Most car and truck enthusiasts are quick to add more power, install more efficient brakes or change wheel and tires combos but haven’t given a second thought of upgrading the vehicle’s lights. A typical enthusiast assumes that light upgrades are mostly for desert and off-road racers or truck drivers. The typical response to an upgrade lighting system experience is “How did I drive without these for so long”. Driver fatigue is greatly reduced and safety is greatly increased. Your drive will feel more relaxed and seem to go by faster when you reduce the typical strain of night driving. Taking your car or truck out at night without upgraded lighting is like going for one more ride with bad brakes. It’s just not safe.
Homogenous Illumination; The best combination of distance, width and height all being evenly illuminated in intensity (Lux) and color (Kelvin) as possible. The object of your vehicles lighting is to illuminate as large an area in the front of the driver as evenly as possible to give as much clear visibility as possible. The most efficient lights create the best balance of these properties. We’ve all seen other drivers whose headlights are intensely bright when viewed directly in front, but have little lateral illumination. An imbalance like this can actually reduce visibility instead of increasing it. An area with too much light (overexposed) can actually reduce visibility. Our eyes continually react to the best light available and like a very sophisticated camera with auto exposure they naturally adjust to the best light available to them. An over exposed area can reduce visibility in the poorly illuminated areas the same as too little light in too small an area affects visibility.
The object of our vehicles lighting system is to illuminate the largest area in the direction of travel as possible. Potential hazards illuminated evenly at the optimum Lux and kelvin allows our eyes to focus as quickly as possible. The intensity (Lux) and the color (kelvin) of that light are the determining factors in how quickly our eyes can clearly focus. Eye strain is a major contributing factor to driver fatigue. The more quickly and clearly our eyes focus will determine hazard perception time, driver reaction time and ultimately driver fatigue. The best lighting systems take into consideration both headlights and driving/fog lights to achieve optimal results for all driving conditions. A good example is LED lights with multiple intense LEDs and high kelvin light output can be good for slow desert driving in confined spaces at low speed, but are highly inadequate for higher speed or highway applications and can actually reduce our distance visibility due to short range overexposure and long range underexposure. In other words they would exhibit poor Homogenous Illumination.
Vehicle lighting has progressed tremendously over the years. Even with these advancements, we are still limited to the amount of power (12 volts) we have to power them. We must create the best combination of Lux and Lumen and we must consider the direction and spread or concentration of light. We must do all this while ensuring the light does not interfere with other driver’s ability to see. This where a light’s lens and reflectors come into play. The reflector will take the light source and project it into the desired focal point. The lens defines the area in both height and width that the light will project to. The combination of the light source, the reflector and the lens will determine the output accuracy and a clear, sharp division from lit areas to non lit areas.
A common misconception is that color temperature (kelvin) equates to brightness. This is not the case. The color temperature is only a reference to the color of the light output. To give you a reference of light colors we’ve assembled a list of typical items and their approximate light color on the kelvin scale.
• 1700 K: match
• 1850 K: candle
• 2700-3300 K: incandescent light bulb
• 3500 K: 100W Halogen light bulb
• 4100 K: moonlight
• 4200 K: 100W Xenon light bulb
• 5000 K: horizon daylight
• 5500-6000 K: daylight
As you can see, the lower on the kelvin scale the yellower the light. The higher you go on the kelvin scale the whiter the light is
Watts? Lux? Lumen?
1. An amount of power, especially electric power, expressed in watts or kilowatts.
2. The electric power required by an appliance or device.
Plural; lumens or lumina
The derived unit used to measure the amount of light passing through a given area per second. One lumen is equal to the luminous flux passing per unit solid angle from a light source with a strength of one candela.
A derived unit of illuminance in photometry, equal to one lumen per square meter.
Wattage does not affect the amount of light output. Watts measure the amount of power used by a given object. In this case the light bulb. Obviously the more power consumed by the bulb the greater the ability to produce light. The most accurate way to measure lights efficiency is to use lux and lumens to objectively measure a performance.
Lumen is not as complicated as the above definition eludes. In laymen’s terms, think of lumens as the total amount of light visible in a beam (flux) emitted from the source. This factor alone does not determine how well a light fixture illuminates the road or an object. It merely quantifies the amount of light output projecting from the fixture.
Lux tells us the amount of light projected over a given area. As you can see from the above definition, lux is the measurement of lumens over 1 square meter. An example of how lux defines a lights projection can be stated like this example; a light that has a light output of 1,000 lumens and covers 1 square meter will illuminated that meter to 1,000 lux. Take the same light and illuminate 10 square meters. The light will now have illuminated the 10 square meters to 100 lux.
We hope this clarifies some common terms and concepts regarding vehicle lighting.