Temperature and light output.

[ericmark]

OK two very similar bulbs, both 5W both LED, Both globe, both 180° both marketed by Ecolight one part number EC79130 the other EC79129 being 6500K +/- 500K and 3000K +/- 200K and 440 lumen and 420 lumen being classed as daylight and Warm White.

I will admit I did not even notice the difference until fitted in the same room, I had 10 x 3W candle fitted in one room, and after fitting 3 daylight globe lamps in the other room, it seemed a good idea to fit globe lamps at 5W to replace the 10 candle 3W bulbs when I had found some where to use the 3W candle bulbs which were being removed.

The gain did not seem to be as much as with other room, but until I fitted three of each in the same room I had not realised one set was day light and the other warm white.

So with the room with 10 lamps, although the 5W were brighter than the 3W, the difference was not that marked. But moved from 2300 lumen to 4200 lumen not quite twice as bright. I should have needed sun glasses.

This is not the first time lumen and brightness perceived does not seem to have lined up. But the two ends of the room with 3 day light and 3 warm white is very marked, OK whiter that is to be expected, but 1320 lumen v 1290 lumen seems very marked, when 2300 lumen v 4200 lumen hard to tell the difference.

What's gone wrong?

 

[JohnW2]

What's gone wrong?

I'm a bit confused by some of your description, but is not one of the issues that human perception of the "brightness" of light from 6500K and 3000K sources might be very different? Even if they should be, in practice lumens are certainly by no means all of the story.

Kind Regards, John

 

[deadshort]

Hi, you need a Lux meter

DS

 

[ericmark]

Hi, you need a Lux meter

DS

What I need is a picture taken with both and look at the meta data but I am not going to put the old bulbs back just to test.

 

[JohnW2]

What I need is a picture taken with both and look at the meta data but I am not going to put the old bulbs back just to test.

Even that will not take the 'human factor' into account. Whilst lux (lumens/m²), unlike W/m², attempt to take human perception (of perceived 'brightness' at different wavelengths) into account, no two humans are identical in their perception, so it can only be an approximate guide.

Kind Regards, John

 

[big-all]

i measure the consumption[input watts]and note the output level against stated watts and lumins
i find a closer range off input voltage will be more efficient as in 185-250v more efficient than 85-260v
indeed i have some bulbs where the output watts are quite high as in 12w that i would say is around 80w normal output but the input is actually half the rated at 6w so actually very bright

so in short i write on every bulb the date bought and the input wattage
i then choose the the ones that give the best output per watt within a type purchased at the same time and another batch or type from another source[usually hk china or uk sourced hong kong supplier]

 

[333rocky333]

we do shopfitting and I notice straightaway if one lamp is 840 cool near a 830 warm, even more so a 865 daylight, however a lot of people say the 865 looks brighter and we do some shops all 865, tesco favour 840 whereas the defunct safeway opted all 830.
personally I find 865 duller and blue compared with 840 and even 835 white

 

[JohnW2]

... a lot of people say the 865 looks brighter .... personally I find 865 duller ...

That underlines what I said about the perception of light (at different wavelengths) being a pretty subjective/individual thing - such that your "A is brighter than B' could be eric's 'B is brighter than A", if A and B had different wavelengths.

Furthermore, as DS has implied, even for one individual, lumens mean little in relation to perceived 'brightness' without knowledge of the distribution of light and the surfaces it is falling on.

Kind Regards, John

 

[ericmark]

I had noted my sons house with 7W spot lights in the kitchen did not look as bright as the living room over twice the size with two standard bulbs in standard pendants. As a result for the main room in my house and mothers we have gone for many small bulbs rather than a few large bulbs as it seems to spread the light better and not have a bright point of light which can distract. Since mother has macular degeneration lighting is important, no super bright lights, but plenty of light, so intend to use 10 x 3W bulbs. My own house has a larger living room so took the chance to up the bulb size to 5W in my house and use the 3W in mothers house.

However although the room is brighter after moving from 10 x 3W to 10 x 5W there is not that much difference, so E14 candle 3W 230V 250 lm 3000k to E14 globe 5W 230 V 420 lm 3000k Ecolight so 250 lm to 420 lm which is quite a jump. But to be frank the difference was not worth the swapping of the bulbs. It should have been like using a 100W bulb instead of a 60W bulb, but it wasn't.

The dinning room actually we dropped in lumen we went from 8W CFL as a globe at 550 lumen to 5W LED at 420 and 440 lumen and the room looks marked brighter. OK may be the CFL have dimmed with time. However it seems lighting a room is just hit and miss, one has not a clue if bright enough until you try them.

 

[bernardgreen]

That underlines what I said about the perception of light (at different wavelengths) being a pretty subjective/individual thing

I agree with that, Some people will see "white" light that is not full spectrum ( made up of just the three primary colours) as having a hue and not as pure white.

 

[JohnW2]

I agree with that, Some people will see "white" light that is not full spectrum ( made up of just the three primary colours) as having a hue and not as pure white.

Indeed, that is certainly true - perception of colour is even more 'individual'. However, as you know, I was talking about the way in which two individuals might perceive the relative brightness of two lights differently, if they have different spectrums.

Kind Regards, John

 

[JohnW2]

The dinning room actually we dropped in lumen we went from 8W CFL as a globe at 550 lumen to 5W LED at 420 and 440 lumen and the room looks marked brighter.

As I've written a number of times recently, I don't think that lumens, on their own, mean very much without knowledge of the distribution of the light. In your example, if (as is quite probable) the LED has a more restricted distribution (e.g. 'narrower beam angle') then I think it's very possible that an illuminated surface would be 'brighter' (i.e. more lux) with a 420 lumen LED than with a 550 lumen CFL.

Kind Regards, John