LED Bulbs

[Soapy Sam]

The fitting in my room has 5 11W LED GU10 bulbs (each with 3 LEDs), plus 1 35W halogen bulb.
When switched on, the halogen bulb lights up about half a second faster than the LEDs, which show a marked delay compared to halogen or tungsten bulbs, though nothing like the CFL lag. Once lit however, the halogen looks noticeably yellower and dimmer. (Some would say "warmer".) The room is very brightly lit. My wife winces when she comes in, but I like it.

 

[wobs]

Measuring light output can be tricky. As you say, you measured lux. Which is a measure for the amount of light at one specific point.

Bulbs are rated in lumen, which is the total light output of the bulb in ALL directions (which is independent of distance. You cannot assign a lux number to a bulb; you have to define at which DISTANCE to measure the lux.)

Total light output is difficult to measure. Professionally it's done with an integrating sphere (a sphere specially coated on the inside to catch and reflect all light, and a bunch of lux meters at special points. The points are chosen based on known lighting geometry of the bulbs).

For humans, the total light output is pretty impossible to sense. We can only sense the brightness that reflects off an object (what you measured with the lux meter), and a difference in output geometry of the light source screws us up.

Another problem I see is the spectral calibration of the light meter. It's possible that it only measures a few wavelengths, which are chosen for an incan spectrum (black body radiation). It measures LEDs and FLs wrong, as they have significant light output in the blues, which the light meter might not measure.

Much appreciated post.
I realised it wasn't the most scientific of measurements, and was hoping someone would critique it.

I've taken the plunge and ordered 4 new LEDs (12w each) for the kitchen. Fingers crossed they are decent ones. They are Samsungs.

 

[xtifr]

Oh, and the reason these spectra are important:

You can fool the eye to recognize white light with as little as two colors (old B/W TV tubes did that), but when the light is reflected from a colored surface, the color is distorted because only the colors actually present in the light are represented.

Hans

And...this is an issue because?...

CFLs produce light that works just fine for me. It allows me to see things. If there's any color distortion going on, I suspect my brain is quickly adjusting for it--just as your brain quickly adjusts if you wear glasses that turn things upside down. In any case, whatever the effect might be, it's too slight for me to have ever noticed.

CFLs have been a big win for me, and their light has never ever bothered me--they do have issues (dimmers, for example), but none that have ever affected me. And they seem to last me 4-6 times as long as incandescents used to. I really suspect that a lot of people are simply looking for excuses to not use them, for various mysterious odd reasons, such as not wanting to try to the new and different, or not wanting to be labelled "hippie", or some such nonsense.

That said, I'll probably switch to LEDs when the bulb price makes them cost effective. They do look like they'll be big winners in the long run. But that day doesn't seem to be here yet. Not quite. Maybe by the time my current batch of CFLs expires--but that shouldn't be for at least another year.

 

[wobs]

LED SMDs are apprarently a good thing:
http://www.lightingmarket.co.uk/faq_info.html?faqs_id=128
http://www.wholesaleledlights.co.uk/blog/2011/11/the-advantages-of-smd-led/

 

[Soapy Sam]

CFLs produce light that works just fine for me. It allows me to see things. If there's any color distortion going on, I suspect my brain is quickly adjusting for it--just as your brain quickly adjusts if you wear glasses that turn things upside down. In any case, whatever the effect might be, it's too slight for me to have ever noticed.

We might say much the same of candles or flaming torches.They let you see things. Personal preference is just that and other peoples' are exactly as real as yours or mine.

CFLs have been a big win for me, and their light has never ever bothered me--they do have issues (dimmers, for example), but none that have ever affected me. And they seem to last me 4-6 times as long as incandescents used to. I really suspect that a lot of people are simply looking for excuses to not use them, for various mysterious odd reasons, such as not wanting to try to the new and different, or not wanting to be labelled "hippie", or some such nonsense.

There I think you are denying others' responses or opinions equal validity with your own . You find CFLs fine- great. I find them slow to light, fast to fade*, and most importantly, I find they give far poorer light than tungstens.
I can't help wondering if, given you seem to find CFLs and tungstens equally acceptable, your eyesight may be either far better or much worse than mine. To me the difference is glaring.

The issue certainly isn't cost, as they were literally being given away free here in the early days to encourage folk to use them and I know a number of people who, like me, still have several in a box, because they tried some and didn't like them. And I don't think anyone would describe me as a hippy. More nerd, really. I'd love new light technology if it gave better light. CFLs don't.

I do agree people often resist new ideas for no very good reason apart from inertia, but I think I also have a right to simply think something is inferior as a product, compared to the product it is intended to replace. I know a lot of folk feel that way about CFLs. They also resent the blatant government & Industry pressure to conform. So I agree there are psychological reasons for resistance to CFLs, but I disagree they are as shallow as you suggest.

Back on LEDs, which are far costlier than either tungsten or CFL bulbs, I and others I know,(none of them very hippyesque) have a very different response: We like the product, because it's clearly superior to older types, but we are not yet mentally ready to pay the up front price, especially if we have a box of old style bulbs under the stair that we like just fine.

That's presumably because we all know that working to cut our power bills is climbing a downhill escalator, since utility companies will simply raise the unit price; whereas the instantaneous cost of half a dozen LED bulbs would raise the cost of my weekly grocery shop by about 50% and would quintuple that of many elderly people living alone- the ones who might benefit most from cutting their bills.
+++

* The life of a CFL is, statistically, longer than an incandescent, but the actual light output falls sharply with time, whereas a tungsten bulb , if clean, tends to maintain it's rated brightness till it fails. This is clear if you ever replace one CFL in a multi bulb-fitting. This I find so obvious that I'm astounded to hear people say they never noticed. I think that's your brain doing the adapting you describe. Lying to you , in short. You're right that it happens, but I see it as a bad thing, whereas you seem to think the opposite. Like I say, we all differ. Use what works for you.

 

[Olowkow]

Since the kind of LED's I bought the other day were perfect for my purposes, I went back to Home Depot and bought 4 more. They were on sale and are Phillips 40 watt equivalent (8 watt) "A Shape" 470 lumens--lifetime 22.8 years, $.96/year. The shape is a bit like a small flood type. I also got some 60 watt ones.

There were three color types: soft white, bright white, and daylight. They had samples of each color lit for demo purposes. "Soft white" was really pretty yellow, "bright white" was less so, and "daylight" was very white with no yellow. I bought all "daylight" bulbs, and now the difference in the kitchen is really striking in terms of illumination compared to CFL's that had been on the track. I find the "daylight" much less gloomy than light with a lot of blue (like standard fluorescents) or yellow.

After installing the bulbs, I couldn't help thinking, "Eat your heart out Michelle Bachmann."

...whereas a tungsten bulb , if clean, tends to maintain it's rated brightness till it fails.

True, but often old incandescent bulbs that survive too long wind up with tungsten coating the inside of the frosted glass, causing the darkening often seen, reducing output. This is why halogens have to be quartz, and run very hot to cycle the tungsten back onto the filament.

 

[marting]

What I don't like about CFLs and LEDs to a lesser extent is that photos, artwork, or even brightly colored cereal boxes produce greatly attenuated reds which look more like a dark reddish orange. This is true even when the color temperature matches an incandescent.

Maybe most people don't notice it but if you look at these under a normal incandescent then under a CFL the difference is very apparent.

Basically, using phosphors that have significant energy in the red spectrum is costly. It reduces the lumen rating of the bulb. This is also why highly efficient (from a watts to lumens pov) industrial fluorescents have a noticeable greenish cast.

 

[Soapy Sam]

I wonder though what negative effects will show up with LEDs over the long term, if any.
One obvious cost is that if you rent an apartment on a short term lease, you are cheaper with almost anything other than LED-unless you take them with you when you move, but do the failure rates go up if you move them?

Incidentally, here's a link showing some typical UK prices for GU10 spotlights.
http://www.thelightbulb.co.uk/product/LED-Lights-Bulbs/LED-GU10/c-338

I don't know why the prices vary so much. Take the 50W equivalents for instance. Prices range from £8.75 to £23.22 from the same website. It's very hard , without knowing a good deal about the technology, to decide what to buy.

With tungsten bulbs, if you bought a cheap one and it blew in a month, you had lost a few pennies. Get it wrong here and you're looking at a cost difference of £10-14 per bulb.

At 16p / kWh, that's over 11000 hours of running time, unless I dropped a decimal.
So should I buy one pricy one or three "cheap" ones? And what if something far better and cheaper comeas along next year? Do I replace the bulbs again? (And put them in the box with the 128MB , 256MB etc USB sticks, the cassette tape collection, record collection, CD collection...)


!

 

[Pulvinar]

What I don't like about CFLs and LEDs to a lesser extent is that photos, artwork, or even brightly colored cereal boxes produce greatly attenuated reds which look more like a dark reddish orange. This is true even when the color temperature matches an incandescent.

Maybe most people don't notice it but if you look at these under a normal incandescent then under a CFL the difference is very apparent.

Basically, using phosphors that have significant energy in the red spectrum is costly. It reduces the lumen rating of the bulb. This is also why highly efficient (from a watts to lumens pov) industrial fluorescents have a noticeable greenish cast.

Do your cereal-box reds look attenuated to you in daylight too?

One might also complain that CDs don't give the nice hiss and popping of "normal sounding" vinyl records...

 

[Earthborn]

In any case, whatever the effect might be, it's too slight for me to have ever noticed.

Get some LEDs and you'll notice. CFLs are acceptable, but LEDs are beautiful.

But that day doesn't seem to be here yet. Not quite.

That day is here, trust me. It has been here since 2010 or so.

That's presumably because we all know that working to cut our power bills is climbing a downhill escalator, since utility companies will simply raise the unit price;

They'll probably will have to raise prices a lot quicker if we keep wasting energy on those silly "heat globes".

whereas the instantaneous cost of half a dozen LED bulbs would raise the cost of my weekly grocery shop by about 50% and would quintuple that of many elderly people living alone- the ones who might benefit most from cutting their bills.

If you have so little savings that you can't afford that 50% extra up front once to start saving loads of money for the next 25 years or so, I guess you could just buy a LED bulb every week instead of 6 in one go.

Maybe most people don't notice it but if you look at these under a normal incandescent then under a CFL the difference is very apparent.

Under a CFL the difference is very apparent. Under a half decent LED it is not.

I don't know why the prices vary so much. Take the 50W equivalents for instance. Prices range from £8.75 to £23.22 from the same website.

The 50W equivalent GU10 LED bulbs I got my parents -- which are fantastic -- cost me just 3 Euros each.

Get it wrong here and you're looking at a cost difference of £10-14 per bulb.

Not really, because you're obviously not going to wait until they blow (that takes forever). Just buy them, and try them immediately. If they don't make you go "Oh... My... God... I never thought light could look this gooooood!" you can take them out and bring them back to the store.

So should I buy one pricy one or three "cheap" ones?

Buy them all.

 

[marting]

Do your cereal-box reds look attenuated to you in daylight too?

One might also complain that CDs don't give the nice hiss and popping of "normal sounding" vinyl records...

That's a completely backwards comparison. CFLs have major deficiencies rendering color accurately unlike daylight or incandescent sources.

\Under a CFL the difference is very apparent. Under a half decent LED it is not.

I agree LEDs are better than CFLs rendering red but the differences are still pretty noticeable to me. Do you have any specific metrics comparing CFLs, LEDs, and incandescents operating at the same color temp. on say, a ColorChecker red patch?

 

[Pulvinar]

That's a completely backwards comparison. CFLs have major deficiencies rendering color accurately unlike daylight or incandescent sources.

Yes, but if you consider incandescent to be normal lighting, then what do consider daylight? You'll get quite different results just between these two sources.

If both of these can be accurate, why couldn't CFL be "accurate CFL illumination"?

 

[marting]

Yes, but if you consider incandescent to be normal lighting, then what do consider daylight? You'll get quite different results just between these two sources.

If both of these can be accurate, why couldn't CFL be "accurate CFL illumination"?

Of course it is "accurate CFL illumination" by definition. Spectrally, CFL illumination doesn't correspond to the normal illuminants such as D50 or D65 or A which roughly, though not precisely, corresponds to perfect black body illuminants at differing temperatures. One is used to daylight varying from a high kelvin temp to a much lower one near sunset. We have adapted to seeing the "same" colors from brightly lit daylight scenes to those near dusk. Standard tungsten lighting corresponds nicely to the lower kelvin equivs. near sunset and the even a 5000K illuminant at 100 lux looks harsh and bluish while, a 50,000 lux illumination at 5000K competing with the Sun at midday will look somewhat yellowish.

In any case colors we are used to seeing in either full daylight, near sunset, or indoors with tungsten light are materially shifted. I, for one, don't like to look at a perfectly good picture of assorted flowers and have the red ones looking like a muddy orange.

 

[Brian-M]

Yes, but if you consider incandescent to be normal lighting, then what do consider daylight? You'll get quite different results just between these two sources.

If both of these can be accurate, why couldn't CFL be "accurate CFL illumination"?

I think he's pointing out that both sunlight and incandescent lighting are products of black-body radiation, and therefore produce light across the entire spectrum (despite having different color temperatures, but the human eye adjusts to that fairly easily).

But CFLs and LEDs have gaps in the spectrum. If an object is reflecting a color in this gap area, the color will look normal in sunlight and incandescent, but dark in CFL and LED.

 

[marting]

Earthborn:

Indeed, measurements on a standard ColorChecker red patch shows the following xyY coordinates (x and y are the cords on the standard xy color gamut, Y is the reflectance relative to a 1=100% reflective surface):

Illuminant A
.633, .339, .367

LED
.597, .354, .337

CFL
.608, .359, .170

Both the color of the CFL and LED are shifted slightly away from red and towards green. The brightness is also lower on the LED but is way lower on the CFL by 50% which accounts for its muddy look.

More info on color gamut and its xy coordinate representation:
http://en.wikipedia.org/wiki/Gamut

 

[Soapy Sam]

They'll probably will have to raise prices a lot quicker if we keep wasting energy on those silly "heat globes".

Not if we are using them as heaters which also give light. But that's an old story.

If you have so little savings that you can't afford that 50% extra up front once to start saving loads of money for the next 25 years or so, I guess you could just buy a LED bulb every week instead of 6 in one go.

I could, but I won't for the same reason I won't buy more food than I need. I have food and I can only eat so much.
I have a lot of old style bulbs and I won't throw them out just because something better is on the market. I'm sat under 5 LEDs right now. They give very clear, bright light. I like them. But I don't like them enough to junk a dozen unused incandescents and half a dozen halogens I already bought, just as I won't junk my 5 year old computer because there are faster ones on the market. (Which might also save me more power than any another half dozen new lamps.)
Also, you maybe missed where I said I don't expect to be alive in 20 years. Besides. I don't believe those estimates. Why should I? And what if some better technology turns up next year? Do I start over?

The 50W equivalent GU10 LED bulbs I got my parents -- which are fantastic -- cost me just 3 Euros each.

Got an address in the UK?

Not really, because you're obviously not going to wait until they blow (that takes forever). Just buy them, and try them immediately. If they don't make you go "Oh... My... God... I never thought light could look this gooooood!" you can take them out and bring them back to the store.

You think a store will give a refund on a used lightbulb? Really?

Buy them all.

Send money.

 

[xtifr]

I find them slow to light, fast to fade*, and most importantly, I find they give far poorer light than tungstens.

Slow-to-light is a hallmark of early CFLs. I remember those, and they were a little annoying, but I haven't stumbled across one with those problems in years. Fast-to-fade may be a bigger concern, but y'know what? I've never once actually noticed this effect, and as far as I'm concerned, a difference that makes no difference is no difference. You're right that I think "my brain is lying to me" is perfectly fine. It's not like I can swap it out for a better brain, and throwing away money to compensate for something my brain can already compensate for just strikes me as silly. Yes, I do think of my brain's adaptability as a positive trait, and I'm amazed to find that someone doesn't.

I can't help wondering if, given you seem to find CFLs and tungstens equally acceptable, your eyesight may be either far better or much worse than mine. To me the difference is glaring.

I certainly notice the difference. It just doesn't bother me. Both allow me to see, which is my goal when turning on a light.

Now, again, I did have a bit of a problem with the light from early CFLs. It generally seemed a little harsh. But since they came out with "warm" CFLs, many years ago, I've been very happy with the quality of light. Sure, it's not daylight, but what is?

(Perhaps ironically, I dislike so-called "daylight" CFLs.)

I'm not denying that there may be people for whom the "quality of light" may be an actual issue. People can be hypersensitive to all sorts of things. But most people aren't, and the number of people who whine about CFLs on Internet forums seems extremely disproportionate to the percentage of people I know in actual life who have a measurable problem with them.

In other words, I tend to classify light snobs along with wine snobs and audiophiles. A group with a tiny handful of sensible people hiding amongst a huge crowd of complete idiots. Of course, I have no idea which category you fall under, so I'm not making personal judgments. But even if your eyes are such that you have a legitimate complaint, you're keeping company with some awfully stupid people, IMO.

And maybe I'm just hypersensitive to throwing away money. I run Linux even though I have friends who assure me that Macs are a whole lot less temperamental.

The issue certainly isn't cost, as they were literally being given away free here in the early days to encourage folk to use them ...

Cost is certainly an issue for me. Incandescents seem like throwing away money. I mean, if someone were to prove that burning dollar bills gave you the purest, most perfect light, I'd still stick with CFLs, and I bet even you would switch to CFLs if those were your only options.

There's a saying in my industry: "the perfect is the enemy of good^WP". Incandescents aren't even perfect, but they certainly seem to me to be way past the point of diminishing returns.

They also resent the blatant government & Industry pressure to conform.

Oh yeah, I forgot about those idiots. Not that I'm not sympathetic to their concerns, but again...burning dollar bills to prove you're not under the thumb of the government/corporations seems like a case of poor priorities.

In any case, I'm pretty sure the industry hates them. They last longer, so reduced sales, and, at least in my state, the industry has to provide recycling facilities.

So I agree there are psychological reasons for resistance to CFLs, but I disagree they are as shallow as you suggest.

I remain unconvinced, even while admitting that there are a tiny percentage of people who may have a legitimate basis for complaint.

Back on LEDs, which are far costlier than either tungsten or CFL bulbs, I and others I know,(none of them very hippyesque) have a very different response: We like the product, because it's clearly superior to older types, but we are not yet mentally ready to pay the up front price, especially if we have a box of old style bulbs under the stair that we like just fine.

Now here we're in complete agreement.

 

[rjh01]

I think he's pointing out that both sunlight and incandescent lighting are products of black-body radiation, and therefore produce light across the entire spectrum (despite having different color temperatures, but the human eye adjusts to that fairly easily).

But CFLs and LEDs have gaps in the spectrum. If an object is reflecting a color in this gap area, the color will look normal in sunlight and incandescent, but dark in CFL and LED.

It is worse than that. Here is something all good photographers know.
1. light an object using only CFLs.
2. Take a photo without flash.
The colours in the photo will appear wrong. Even though our eyes tell us the colours appear normal. May work with other types of bulbs such as LEDs.

 

[elgarak]

It is worse than that. Here is something all good photographers know.
1. light an object using only CFLs.
2. Take a photo without flash.
The colours in the photo will appear wrongdifferent. Even though our eyes tell us the colours appear normal. May work with other types of bulbs such as LEDs.

Our eyes evolved to see black body radiation style spectra (actually, just one spectrum, that of the sun). For millennia, the only artificial light we had was black body radiation of various color temps.

Analog photography was developed with black body radiation spectra in mind, because it was the only game in town.

Spectra of FLs and LEDs are different, and new. But, the way I see it, they're here to stay, LEDs in particular. As a photographer, you have to evolve to deal with that. Digital photography can deal with the color changes quite nicely; even cheap cameras have a setting for FL lighting, and you can adjust the colors in post. Of course, when you present your work, you have to make the print with the lighting at the showroom in mind. You always had to that, BTW. It's just that in the past all spectra were black body, and the color temp and its effect on the colors of the photo could be calculated. FLs and LEDs are more complicated, as they may have vastly different spectra that are not easily calculable with a simple number like color temp.

 

[Soapy Sam]

Here's something to try while we save up to buy LEDs.
Bring your own Bottle.
http://www.bbc.co.uk/news/magazine-23536914