Light Power & Colour

The distinctive purer white light of HID lamps stimulates the reflective paints in road markers and signs creating a safer driving environment. Additionally, the increased light output is designed to illuminate a wider area in front of the vehicle, improving visibility and safety, without disturbing the vision of oncoming drivers.

The following is a chart that illustrates the distribution of illumination in 35 watt HIDs.

(note 50 watt HIDs are considerably brighter)

Efficiency of HID light

HID lamps put out around four times the lumens per watt of traditional halogen light sources and are far more efficient at converting electrical energy into light. By using more of the electrical energy to produce light, the HID lights also waste considerably less energy in the form of heat, and run considerably cooler that Halogen bulbs.

HID general lighting has been used for years in sports arenas and stadiums around the world and comes in many forms, all typically producing between 90 and 110 lumens of light per watt. This compares with Halogen lights which produce around 25 lumens per watt.

Some specialised forms of HID light (Low Pressure Sodium) produce up to 183 lumens per watt. These are not suitable for vehicles however due to the 5-10 minute time lag between igniting and full brightness.

Longevity of HID lamps

HID ballasts and burners are designed to operate for 3000+ hours of operation. In most cases that is as long as the vehicle life itself. Compare this to a regular halogen bulb, whose expected lifespan from new is a mere 500 hours, or to a overdriven halogen bulb such as a PIAA 55=110, where the life expectancy is a mere 250-300 hours. Once installed, your HID light source is unlikely to need to be changed for at least 100,000 miles.

HID lamps (like other lamps, including halogen lamps) do lose brightness over time. You can expect any and all HIDs to lose up to 25% of their brightness by around 2000 hours of use.

For peace of mind, HID50 do sell replacement HID bulbs in the standard fitments and colours.

What is a Lumen (lm)?

The lumen (symbol: lm) is the standard unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light. By example

830 - 850 lm 60-watt tungsten bulb
1250 - 1400 lm : 55 watt standard H7 halogen bulb
1500 - 1650 lm : 55 watt performance H7 halogen bulb (Philips 50+, PIAA 55=110 etc)
3000 - 3200 lm : 35 watt HID conversion
4600 - 5300 lm : 50 watt HID conversion

In essence, the lumens represent the illuminating power of the light source, as seen by the human eye. A 35 watt HID gives out over twice the illumination of a halogen bulb, while a 50 watt HID gives out over three times the illumination.

The relative power (efficiency) of various lights:

15 lm / watt : tungsten bulb
25 lm / watt : halogen bulb
70 lm / watt : 3rd Gen Luxeon LEDs
95 lm / watt : Vehicular HIDs

So you can see that HIDs give the most bang for buck of any vehicular light source.

The following image compares mere 35 watt HIDs with 55 watt halogens

Light Colour

The colour of light is represented by the temperature in degrees Kelvin (Kelvin is a basic unit of thermodynamic temperature). White light is at 5600K.

1800 K - Candlelight
2700 K - Tungsten bulb (house bulbs, parking lights, sealed beams)
3200 K - Halogen bulb (uses tungsten filament)
4300 K - OEM HID light
5500 K - Camera flash
5600 K - White light reference point (midsummer sunlight, Washington DC)
5800 K - Directly overhead sunlight at the equator (the surface temp of the sun)
7000 - 12000K - light under overcast skies (reduced contrast)
12000 K and up - Ultra Violet light

Lighting for photography and movie work is typically either at 5000K, 5500K or 5600K. By choosing HIDs at either 5000K or 6000K you will get the whitest light. Light at a source below 5000K takes on an increasingly yellow tinge, while light above 6000K becomes increasingly blue and purple. Contrast is strongest to the human eye when light has a slight yellow tinge (thus high contrast glasses and ski goggles are yellow-orange) and light beyond 6000 K sees contrast fall dramatically. 5000K light offers slightly higher contrast for the human eye than 6000K light. On the other hand 6000K light has a very attractive purity to it as it is the closest HID colour to overhead sunlight.

AT HID50, we recommend and stock only 2 colours, 5000K and 6000K. If you specifically want a colour outside those colours, and you are aware of the limitations of light outside those colours, then we can get in other HID colours in on a special order, and for a small premium.

*** Note that Original fit HID bulbs on cars are typically at 4300K. Why is that less suitable for conversions? OEM HIDs in cars are designed with dichroic projector lamps that split the colour of the HID light. That�s why from some angles (particularly close to the cutoff) the OEM HIDs look blue (beyond 6000K) and from other angles they look as yellow as halogen lights (3000K). The bulk of the light they throw forward however is around 5000K. When you convert a OEM halogen light to HID, you will not have a dichroic projector lamp specifically designed for HIDs. Therefore to get a similar colour to the OEM HIDs, you need to use 5000 or 6000K. If you choose 4300K, WITHOUT having a dichroic projector light unit, you will end up with a yellowy beam.

The labelled light colour on an HID bulb is an average that it will maintain over 2-3000 hours. After passing around 100-500 hours a colour shift will take place. Colour will change slightly. The magnitude of colour shift will vary depending on brand, model and rated colour. It is a very gradual change and unless paid close attention to, an owner is unlikely to notice. OEM 4100K Bulbs manufactured by Philips has a colour shift of approx 250K after 500 hours, which will bring it to up to 4350K. Other bulbs may experience a shift lower in colour, but not by more that 200K