The world of Lighting has undergone many changes in the last century. This means we now enjoy some of the brightest, longest lasting and efficient lighting systems the world has ever seen.

The down side is this has led to an abundance of terminology that many find confusing. The team at Ultra Vision has tried to explain some of these terms.

What is the Difference Between Lumen and Lux?

Lumen is the measurement/output of light produced from a lamp.

Lux is the measurement of light at a specific point or position.

Lumens can be split into 2 groups:  Raw Lumens & Effective Lumens

Raw Lumens is the light output quoted by the manufacturer of the LED.

Example: Cree XM-L2 10w LED has a Manufacturer Raw Lumen figure of 1050 Lumens. If you have 8 of these in 1 lamp the Raw Lumens for that lamp is 8 x 1050 = 8400 Lumens Raw.

Effective Lumens is the actual measured Lumen figure that takes into account real losses e.g. Thermal loss, Optical Loss & Assembly loss.

Example:  Thermal loss, Optical Loss & Assembly/Circuitry/Electronic loss, can equate/effect up to 25% typical lumen loss eg:  8400 Raw Lumens = 6300 Effective Lumens. Other lighting companies have up to 35% Lumen loss due to bad thermal designs, bad housing designs and cheap optics.

Lux is a world-wide term for the measurement of light on a specific surface.  It requires the use of a lux meter which measures the light output.  1 lux of light is equivalent to a full moon at night in good atmospheric conditions.

What is the Relationship Between Watts & Lumen?

If you have two lights in front of you, with one being 75 watts and the other 100 watts, which will produce more light? Most would say the 100 watt light, but that’s not necessarily the correct answer. Truth be told we can’t tell you the correct answer because watts is not a measure of light output. Watts are actually a measure of total power output. Not all of the energy emitted by a light source is visible light – heat and invisible light waves (infrared light) are also emitted. Lumens, on the other hand, will tell you the total visible light output of a source. For this reason, Lumens (not watts) is the relevant measure when you’re concerned about visibility.

What Does the Kelvin Rating of the Lamp Refer To?

The kelvin (K) of a lamp refers to the colour temperature of the light the lamps produces. Most lighting is manufactured between the colour of 2800K – 6500K. 2800K is the yellow side of the colour spectrum whereas the 6500K is a very white light, as you go higher than 6500K the light starts becoming blue and eventually will get to purple. Most normal household halogen or incandescent bulbs are around 2800K whereas vehicles halogen head lights are around 3400K. H.I.D Xenon bulbs are mostly produced between 4200K & 8000K but both higher and lower ratings are easily manufactured, but less useful. All our HID lamps are standard at 6000K but we do offer 4300K as an option. L.E.D’s come in a huge range of colours too, but most of Ultra Vision lights feature 5500K – The colour of daylight. We chose this colour as is it an excellent balance of both light output and light colour (it is easy on the human eye).

What is the Different Between Raw & Effective Lumens?

Why do Some Manufacturers use 1W and Others 5W LEDS?

What‘s Covered by Ultra-Vision’s Five Year Warranty?

Why do you need to worry about LED’s getting hot?

Most people think LED’s never fail, this is not true. A LED’s biggest threat is heat; this is why one of the greatest challenges in producing an LED lamp is thermal management (keeping the heat under control). LED’s also producing less light as they get hotter. LED Manufacturers typically measure the light produced by their LED’s after 25 milliseconds (ms). That is equivalent to a flash. It gives a Lumen number that is the absolute maximum value at the peak of the flash test. LED’s also generate a tremendous amount of power in a relatively small area. As the LED’s are powered for longer and longer periods of time, they typically get hotter and hotter depending on the thermal management system. It’s not unusual for LED’s to reach over 100 Degrees C. For vehicle or machinery applications, most specifications require that the lamp be measured at 10 minutes and 30 minutes to make sure that the LED Temperature has stabilised. This will result in the LED producing 10% -20% less light than its advertised value (this is taken into account with the effective lumens).

This is the reason for LED lamp housings are manufactured from aluminium (excellent thermal conductor) and feature large cooling fins. The aluminium housing and fins are just the beginning in transferring the heat away from the LED. Graphite pads, thermal paste, specialised circuitry and PCB boards also help in keeping the LED’s cool.

How do different LED’s vary in Light Output?

LED’s are available in a huge range wattages and sizes. Generally speaking the greater the wattage, the brighter the LED. This is not always correct and in some cases, some LED’s produce more lumens per watt. LED technology is advancing extremely fast, when LED’s first took the market by a storm they were producing about 80-90 lumens per watt. Now the new LED’s are producing up to 130 lumens per watt. This therefore means you are getting more light for less current draw. See below for more info on Lumens & Watts.

Whiter LED’s have higher lumen output than more yellow LED’s.

Some manufactures specialise in only high-power LED’s while others provide both high power & mid power LED’s.

Does an Optics Over the LED’s Reduce the Light Output?

As light travels through an object such as a lens, it loses intensity depending on the clarity of the material. This is due to inherent losses internal to the material and to losses as light travels from air through the lens back to air. These losses are present no matter the type of light. The losses associated with the lens material and optics can vary from 5% to 20%. An open optic lamp will produce higher effective lumens as the light doesn’t have to shine through anything, but the reflector of the open optic has to be precisely focused to get the maximum result from the LED. A dirty, scratched or dull lens or reflector will greatly affect the beam of light.

What is a Multi Surface Reflector & Why is it Better?

A Multi Surface Reflector or MSR is a reflector that spreads the light rather than relying on a lined lens over the front of the lamp to spread the light. An example of a lamp that features the MSR is the Quattro Elite driving light. A MSR reflector features very faint creases on the back of the lens, these are designed by using a special program to ensure the right shaped spread beam is achieved. Lamps with a lined lens produce less light, as the lens cuts back a huge amount of light output produced from the bulb. This can be likened to a light shining through opaque glass.

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