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Background information Illuminant

Hartenberger LED-Module für UW-Kleinleuchte/Stableuchte

Hartenberger Unterwassertechnische Geräte GmbH - Konzeption mit Know-How

LED-Module (25/60W - 14W - 14W - 21W)


The efficiency of an illuminant is determined by the ratio of accepting energy to yielding luminous flux.
The unit of measurement is lumen per watt (lm/W).

Below are listed some comparative values for common illuminants in the order of their efficiency
(Issue 07.2020)
Light bulb
approx. 15 lm/W
Halogen bulb (do-it-yourself store)
approx. 25 lm/W
Cold-beam bulb
approx. 30 lm/W
Halogen bulb HLX
approx. 35 lm/W
10W/21W/24W (Brightstar) HID lamp
approx. 60 lm/W
Energy-saving lamp
approx. 65 lm/W
Warm LED 3,5 W (Light-Emitting-Diode)*
approx. 85 lm/W
Fluorescent lamp
approx. 95 lm/W
35W D2 gas discharge lamp ( HID)
approx. 90 lm/W
White LED 3,5 W (Light-Emitting-Diode)*
approx. 120 lm/W

*The data given above is the actual light emission from a lamp under practical subaquatic conditions/cooling and continuous operation.

The data given by the manufacturers of LEDs (e.g. 150 lm/W) is based on laboratory tests at a maximum temperature of 25°C and is achieved for a fraction of a second. The operation is however actually performed at approx. one third of the maximum power output. If more power is provided to the LED as is the case in practical use, the resulting amount of light per watt (lm/W) actually decreases.

Unfortunately, most manufacturers of underwater lamps simply copy these non-field performance data in their technical data sheets.

Since the beginning of 2010 Hartenberger has incorporated the latest generation of LEDs in our products and these far exceed the efficiency of halogen bulbs even under field conditions. LEDs are being continuously improved and although the research has slowed down to some extent.

We can assure our customers that we will use the most effective and efficient light elements available on the market in our products and combine these with the optimum conditions and monitoring (cooling and electronic controls).


LED-Module 25W

LED-Module 21W



Any energy that is put into a bulb or LED is only partially converted into light, the rest is converted into heat. Therefore the LEDs produced currently only generate slightly less heat than the most efficient halogen bulb. (based on information available in Jan. 2011). The claims of some dealers of LED lights is therefore uncomprehendable to us.
The majority of the heat that is yielded by halogen bulbs is emitted forwards through the reflector. Therefore, the beam is relatively warm. However, the beam of an LED is almost cold. Therefore, the complete heat of the light-producing semiconductor has to be dissipated "backwards" through the printed circuit board / cooling surface.

In order not to destroy a high-power LED it should only be operated for a few seconds without adequate heat-dissipation / cooling.
These circumstances demand an increased constructive effort in order to ensure the necessary heat-dissipation / cooling.

An overload protection prevents excessive overheating of the high-power LED if cooled down badly, and lowers the power consumption.

LEDs do not produce a balanced colour spectrum of light. The red colour is very poorly generated. The colour temperature of white LEDs is approx. 6000K.

Your can find more information and descriptions about our LED modules under LED-Technology (LED-Technics)


35W HID Mega D2

10W HID Module Tech-Light



The colours spectrum from gas discharge elements (HID - High Intensity Discharge) perform very similar to the LED.
Compared to our high performance HLX halogen bulb, the efficiency is approx 2-3 times better (see the comparison table for standard light elements). We use a 35W gas discharge element common in the auto industry in our Mega D2 lamp. The lamp has a colour temperature of approx. 4300K.




A 10W gas discharge element common in the medical industry is used in our Switch-Module for Tech-Lights.
The lamp has a colour temperature of approx. 6000K.

Due to the mechanical sensitivity no longer available




Halogen bulbs produce the complete spectrum of colours. The red tones are particularly well produced although a large portion of the energy is converted into infra red (heat) radiation. For this reason, we utilise an aluminium reflector that reflects the heat out through the front of the lamp and thus prevents excessive heat build up and/or possible overheating inside the lamp.

Some manufacturers use so-called cold light reflectors made out of coated glass (common in household low voltage light applications). Unfortunately, this material allows the infra red radiation to pass back through the reflector to the rear of the lamp. The build up of heat creates a danger of overheating immediately behind the reflector and the life expectancy of components is shortened considerably.

In a cold light reflector, the invisible infra red portions of light are not exactly separated from the visible red light portions.
This bundling results in a large part of this visible red light, that is especially desirable under water, being absorbed.

The HLX-Halogen bulbs used in our lamps are filled with xenon gas and are particularly effective in producing light. The bulbs have a life expectancy of approx. 100 hours. The colour temperature is approx. 3600K.
Halogen bulbs are however commonly available on the household/DIY market. These bulbs usually have a comparatively low effectiveness in producing light but therefore have an extended life efficiency of approx. 2000 hours.
One of our 50W HLX-Halogen bulbs, powered with controlled over voltage has an equivalent light emmission to a 100W "DIY Bulb".



Colour reproduction with different types of light


LED-illuminant 6000 K


LED-illuminant 6000K

High efficiency. Very cold, blue light with very good penetration properties but a very poor imaging of red colours.

For example; the reproduction of red colours with a gas discharge iluminant from Welch-Allyn (10/18/21/24W), is equivalent to the picture shown on the left with LED illuminant.

Corals, sponges or fish take on a reddish-brown tint similar to that of a house brick.

LED-illuminant 3500 K

LED-illuminant 3500K

Poor efficiency. Warm (golden) light with reduced penetration properties in addition to a poor reproduction of red colours.

Also known as daylight LEDs; these illuminants are poor in reproducing red colours.

Corals, sponges or fish take on a reddish-brown tint similar to that of a house brick.

D2 HID illuminant 4300 K

D2 HID-illuminant 4300K

Very good efficiency. Cold, blue light with good penetration properties and with respectable red colour reproduction.

Coral, sponges or fish reflect an average red.

The Osram D2 illuminant used in our lamps megaD2 and megaD2 Video has the best red colour reproduction properties available on the market of gas discharge bulbs.


LED-R -illuminant with Red-Light-Compensation

LED-R-illuminant with

Good efficiency. Very cold, blue light with very good penetration properties and a good red colour reproduction.

Coral, sponges or fish radiate a rich red colour.

The best choice for divers who do not exclusively divie in fresh water and/or caves. The LED-R is available for the nano compact, mini & maxi compact LCD and for the Tech Lamps.

HLX Halogen illuminant 3600 K

Halogen illuminant 3600K

Acceptable efficiency. Warm, red light with reduced penetration properties but excellent red colour reproduction.

Coral, sponges or fish radiate a very rich red colour.

For divers who wish to use their lamp for optimum colour reproduction in tropical waters

Halogen illuminant 3200 K

Halogen illuminant 3200K

Poor efficiency. Very warm, red light with restricted penetration properties and an overdone red colour reproduction similar to a TV screen with the colour set to max..

Coral, sponges or fish radiate an exorbitant, unnatural red colour.

Usually found in home made lamps with limited technology (absence of over- voltage supply and electronics) and/or lamps fitted with the so-called DIY store bulbs.




For dives in fresh water, poor visibilty or dark conditions, for night dives and for cave diving, we recommend a standard LED element.

Using a daylight LED element is pointless because the advantage of this type of light is not important in these conditions and the red colour reproduction is poor.

Our Mega D2 equipped with the Osram Gas Discharge element has the best performance and is a good compromise when it comes to red colour reproduction. Thanks to the blue elements in the light, the penetration is very good and the red colour reproduction is quite acceptable.

The Halogen bulb with 3600 K is the best choice for tropical waters with it´s natural red colour reproduction.

Our new LED-R module with red light compensation is an ideal choice as the perfect all-rounder.