Glad that the debate on LEDs is taking shape ...
Some pitfalls to avoid however ...
- At the same consumption in watt, we get a different number of lumens depending on the LED performance. So it is better to avoid bulb LEDs, which have a much lower yield than SMD LEDs, or chip-LEDs (except Cree) and among SMD LEDs too, there is food and drink, you get 20 watt will produce 2400 lumens, while others at 30 watt will produce only 1800 lm ... (the more lm, the more light it gives ...)
- The best LEDs (consumption watt / h VS production of lumens) are not Chinese but Amérloquoise (the "Cree").
Did67 wrote:90 lm per Watt is a bit of my benchmark [...] I acquired some cold LEDs, and here it is freezing!
- To have "freezing" cold light, it would have to be between 7 ° K and 000 ° K, we find it extremely rarely (except on the web);
- Lumens have absolutely nothing to do with color temperature (° K). However a neutral light without dominant, will tend to "illuminate better" for our eye than a yellow-orange light where we will have more effort to make to distinguish things (although apparently, the tones will be less shimmering, apparently only. because in fact - since these are neutral tones - it will be the objects around us that will not ...);
- we should not confuse the color temperature in ° K seen by our eyes (the photographic) and that of the light source ...
LIGHT SOURCE:
- The higher the ° K (> 6'500 ° K) the more blue the light will be;
- Those who claim on the packaging that 5'000 ° K is "daylight" are mistaken (it is a low limit not to be below this, already in warm color temperatures, even if that remains white, below it becomes frankly more and more yellow-orange, and therefore less and less neutral for our eyes ...)
PHOTOGRAPHIC:
- The lower the settings for ° K, the more blue the photographic rendering (so it's the reverse);
Hence the frequent confusion ...
- With any light source, the lower the ° K will be (<6'000 ° K) the more the light will be yellow-orange (up to the awful colors of tungsten lamps, but some like it, even if not at all our eyes...);
WHILE FOR OUR EYES THE IDEAL BDB IS 5 ° K for the vast majority of people (see the Kodak and Konika studies, in the 250s, tested on thousands of people.)
Proof of this is the success of xenon lamps (VS halogen) our eyes prefer "daylight" for the lighting produced by car headlights ...
In summary:
- good performance for 10 watt LEDs, it will be ≥1'400 lm ("ok" from 1'200 lm);
- below these yields, there is nothing exceptional (<900 lm, the price must be seen ... So LED bulbs, yield at 90 lm / Watt we are already in old technologies, even the hard-discounters sometimes do better);
- a good neutral color temperature for LEDs, it will be between 6'000 ° K and 6'500 ° K (below you tire your eyes, above it becomes "cold" as color rendering);
Also be careful at one point, I gave up importing them for insurance reasons. In the event of a fire, if it is "regulatory" equipment, insurance companies will not have this pretext to reduce their benefits ...