Per give an idea of what “degrees Kelvin” we can consider that the sunlight at noon is around 5,400 kelvins. Then the LED lamps and HID are closest to natural sunlight and natural light should be the reference. You don’t have to light possible, it should be the right light!
Anyway, day all the lights and HID our eyes have a very low yield, because they emit light more or less of the same quality as that of the surrounding environment.
It would be like writing with a white marker on a whiteboard: how big is the stretch our chariots do not see white on white. If on the contrary the Blackboard is black, so the white marker has a great yield. During a night dive for example HID flashlights and LEDs are great and with the same power consumption outperforms the halogen flashlights defined by LIGHTINGHOWTO.
By day the halogen bulbs are best placed, as they do a light other, warmer than daylight, so that even if they do not emit the same amount of light that is more visible. To continue the example of the Board, would be how to write with a yellow marker on a whiteboard: our eyes yellow is more visible than white.
L a HID lamp emits 1,500 lumens, as from 21 W 50 W halogen survoltata (such as always great “Alulight 50” produced by Technisub) to indicate the “brightness” the lumens are more indicative of Watts, indicating the consumption but not the brightness, so cannot be used to measure the HID and LED, which have a much higher yield Lm/W at halogen lamps.
However, even the lumens are particularly indicative of the efficiency of a light source, for example if there are LED bulbs that emit a lot of lumens, but don’t have the penetration of HID lamps.Therefore, to measure the “penetration” are important the Lux issued from the lamp.
As an example, in comparison with an LED lamp, albeit great, 3,500 2,500 Lux at 3 meters against emanates HID Lux. The halogen spotlight, instead, it ranks far below the HID also consumes the same Lumen halogen 50 W and HID just 21 w. so a battery with the HID lamp lasts more than twice. Certainly a HID lamp from 21 W “K Style” (i.e. with a separate head with handle Goodman, connected to battery canister with a cable) is expensive, but it is absolutely another level, than, say an ubiquitous halogen as the Fa & Mi from 50 W.
Regarding the LED then, first generation products must be distinguished from those left on the market more recently. For technical diving today is still preferable to a HID lamp, but care must be taken because no later than 2013 will LED with better performance than the current 21 Watt HID lamps.
C right there are differences between the light emitted by a HID 21 W and 50 W halogen. If a HID 21 W 50 W halogen 1,500 Lumens delivering as one, it is obvious that the light of the first will be a little more insightful, especially if you can squeeze a lot the beam, but more or less the amount of light output is the same. The difference besides the fire, especially in duration and color of light. A 50 W halogen spot makes the right light intensity, but the problem is the limited duration (maximum 50-55 minutes). Instead HID 21 W solves this problem, to an equal or higher light intensity. The LED is a middle ground: If you want to exceed the intensity of LEDS with a 50 W halogen or HID 21 W, batteries consume too much, the heat dissipated is high and there is currently a problem like a beam in the optical shake HID. Therefore, at the present time, still it is not easy to surpass the performance of HID without loss of life. However, as mentioned above, technology is evolving very fast. You have to follow it.