LED Light: Appearances Can Be Deceiving

The perception of light is a very subjective matter. Regardless of the already very individually distinctive abilities of human Sehwerkzeuge, you will find hardly two people, that exactly the same judge the appearance of an LED lamp. Even a single person can perceive differently a light image because of the training – adjustment effects after a few minutes as at the start – although nothing has changed in reality. Digital cameras usually fail supposedly objective on the truly realistic reproduction of brightness, color temperature and distribution of LED light; even the values of expensive instruments offer a few clues, but often not the full truth.

Traditional David against modern Goliath: A clear 60-watt incandescent bulb with aluminous flux of 680 lumen (package information) and a Matt 10 Watt G95-“Globe” by LEDON 600 lumens.

There is partly fierce discussion in various forums and review platforms on the quality of LED lamps and their suitability as acceptable “Retrofit”replacement for conventional filament and halogen bulb. Apart from the massive price difference, divide the spirits especially on the different perception of light colours and light intensity distributions of old and new technology. Despite steady further development of LED technology, there are these differences actually still as the illuminated pictures of lamps shown above:

The 60W-Glühlampe: Except for the color temperature of approximately 2500 to 2600Kelvin and the extensive full-circle lights image a single falls into the digital photo, especially bright radiation causes to the left above on – possibly from the position of the filament or any reflection. The eye hardly perceives this deviation, however.

The light image of the LEDON G95: “Colder” light color with 2700 K and lower emission downwards, otherwise very evenly.

The assessments of the quality of light of the 176 grams heavy LEDON-“Globes” (at the time in the Company’s own online shop sold out) at amazon.de extends from:

The light from this lamp differs greatly from the light of incandescent, compact fluorescent lamps and also of the 5 Watt LEDON candle! The light from this lamp of LEDON has a “neutral”, as the light of other lamps, has however immediately after switching on a pink tint, which disappears after a few minutes most of. … For me, this light is a light for general illumination – in a stairwell in the ante-room, in the kitchen, or in the den – a mood lighting for the living room it is definitely not.

… about:

The light is noticeably “natural” than that of the compact tubes (“CFLs”), does not match but always still in the classic light bulb. In particular a lighter pink stitch is striking. Wood and white has still not “natural”.

… up to:

How at my other Ledon lamps do I find the light in this lamp very pleasant. For me it compete with a 60 watt bulb on all cases. I can detect no difference regarding the brightness, it not flickers and has also no appreciable delay. The light is really warm and not so sterile as an energy-saving lamp.

The partly perceived “pink stitch” is probably that in the lamp not only five white and four red single LEDs, to achieve the desired colour temperature (PR image left, the designation “2500 K” coincides with the officially specified 2700 Kelvin). Here several factors making their presence felt in the assessment: different sensitive “L-cones” (red receptors) in the eyes of the Viewer, the subconscious “white balance” of the brain (which is also not exactly the same work for each), light series scatters in the LED production and which physically boost led conditionalcolor temperature (so “colder light, even if it sounds paradoxical) with increasing lamp and ambient temperature. The base of this G95 can be hot during extended operation well above 60 degrees – even 85 degrees would be acceptable for the electronics.
In such a “retro” outdoor light the LEDON-G95-“Monster-Globe” fits with its almost 10 cm in diameter and 17 cm length ‘ pure. There he is not uncomfortable with its light color.

In my experience, even the gradual habituation to a different kind of lighting should not be underestimated. Who has completely switched his apartment to ordinary light, more has no direct A/B comparison with conventional light bulbs and no longer missed the “heat” after a while.

You might know this effect from the road: the first Xenon headlamps were still as colorful dogs and worked in the oncoming traffic or rear-view mirror extremely disturbing. Meanwhile sees them – also because of their improved control technology – hardly as something special.

Who believes now but to get the thing with exact science on the track, could be disappointed. Even the values of long and expensive series of tests can supply only a few clues and corner in the assessment of LED lamps. Check out this snippet from a measurement protocol are:

It’s a GU10 LED spot, so will not go into production (therefore, I leave the origin in the dark – he has to do nothing with LEDON but by far). A light output of 165 lumens at a pretty “neutral white” colour temperature of well 3300 K (spectral diagram above right, the circle is the neutral “white point”, the cross the colour of the LED spots on the “Planck’s black body curve”), a strong emphasis of the yellow and red and a weaker of the blue area (wavelength curve top left), a color rendering index of around 77 CRI: all sounds for the first time after a quite useful LED spotlight for kitchen, Bathroom or Office. Not a top of the line and also not very suitable for living room, but a good average for the “low budget”area.

So far, her grey theory. A couple of notes that the spot in practice but is no revelation, deliver the 15 individual parameters for the color fidelity. While playback of “Yellow-green” peaks over 90 (R3) and “Leaf green related” (R14), little happened during “Lilac violet” (R8) and “Blue saturated” (R12) and when my favorite test color “Saturated red” (R9) with a value of less than about 9 almost nothing available. Experienced surgeons among my readers (if any) now know: this lamp in the OP would be out of place, because one could distinguish blood in their light of inflammatory secretions.

(Before you curse me now because of deliberate release of disgust: actually are physicians who put special emphasis on the R9 playback because of wound appearance.) Sharp LED modules provide even values above 95 for the surgical area and other sensitive applications. Similar requirements have also owners of fiery red DUCATIS, time to bring a healthier example.)

Generally now falter “white” LEDs in red – this handicap can be mitigated somewhat by adding Red LEDs (how about LEDON and “DeLOCK lighting” do their larger lamps). The here described GU10 spot has something like that, most branded products from this category and performance class nor. Nevertheless, there are striking differences.

The “no name” spot looks with its three LEDs switched – photographed with very short exposure:

Strange light color, or? And if you want to see now an example for R9 colour reproduction, then I could show a picture with blood you maybe. No? Prefer something else? Okay, then let’s stop the Red model Ducati 916 known already from My fidelity comparison :

UM Yes, that should be “Red saturated” and the pad actually glossy white. Not much better, also, the color in the face of a completely healthy and slightly tanned person looks at this light. “Misogynist” or “Wan” still the friendliest, what occurs to me this – doesn’t matter what readings to say.

The principal of this trial spots way, believes that his clients rarely wanted a “rather yellowish” color temperature of 2700 K. Usually, the range of 3100 to 3300 K sufficient completely. The color rendering index of 77 was “super”, usual LED lamps have only 70. The single value R9 appear low, here but most have products on the market only minus 20 and 30. To get a value by more than + 5, made the fewest providers. Last but not least, it was also a question of the budget and of the planned sale price.

I must confess that I disagree in almost every point (except the last). And your/you?

  1. S.: See also the transcript of rather interestingLamps chats by “Stiftung Warentest”this Wednesday – with confused or disappointed LED customers and the informative note of the expert Peter Schick:

“Germany is in demand usually warm white lamp purchase, approx. 2700 Kelvin.”

 

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