Lighting psychology

[qwertyydude]

You know I wonder just how much value people put on the tint of their home lighting. There are still a lot of people who will say cfl's look horrible. But it's funny but I had one of those types in my room before, one who pointed to various articles saying the light was harsh and bad for you, and she (Strangely it's always women who complain about the look of the light) saw my room and said it was surprisingly well lit and soothing. And I told her it was still a cfl, and all of a sudden her opinion changed, not of cfl's but that my light was giving her a headache! I tried to tell her it's all in her head and the reason my light was nice and soothing is because I have a very large diffuser, which happens to also be a hanging sculpture. The light is so diffuse that there are practically no shadows from objects more than about a foot off the ground.

So my point is if cfl light were the first one's invented, how much do you think people would be complaining about how unnatural incandescent light looks, because personally I think a good cfl tint looks better than a regular incandescent, much more like daylight. And a really warm incan with a CRI of 100 doesn't look as good as a warm to cool white cfl of only around 80.

 

[StarHalo]

How warm or cool your room lighting is should be determined by the design and decor of the room - and when you get it right, everyone will enjoy the lighting so much that they won't know or care if it's CFL or incan.

I've gotten spectacular results from the better quality CFLs, particularly Sylvania brand. Their 3000K bulb is indiscernible from a top-shelf incan, I've had both in the same room and you can't tell which is which. And their 3500K bulb has color rendering like I've never seen from a fluorescent bulb, most likely in the mid to upper 80's, but since the tint is so neutral everything really pops.

 

[hank]

Two different issues -- "warm/cool" or "color temperature" is how the light appears to the eye, a single number/value. With an incandescent (including halogen) you get a continuous spectrum, with a peak somewhere.

The spectra of CFLs (and LEDs) isn't continuous -- it's a collection of narrow spikes emitted by the ionized mercury vapor (inside the fluorescent), or a single color from the primary emitter in the LED. Those then excite other material around it contributing additional spikes.

Craig's really good on this stuff. He's a resource for the world.
http://home.att.net/~ledmuseum/spectra7.htm
I've sent him a variety of lights over the years, to find out what the actual spectra looked like.

For home use we choose CFLs and LEDS (and some halogens) that emit in the range that suppresses sleep (for use in the daytime) and switch to CFLs filtered in that range, and amber LEDs, after around 8pm. But that doesn't refer to color temperature/warm-cool.

We use quite a variety of warm and cool CFLs for daytime use -- all of them have the standard blue-green spike in the spectra. For evening use they range from a "gaslight yellow" (decent color rendering but low emission in the blue-green), to a pure buglight yellow CFL.

Those are all among the spectra Craig has on his page. Useful stuff.

 

[2xTrinity]

You know I wonder just how much value people put on the tint of their home lighting. There are still a lot of people who will say cfl's look horrible. But it's funny but I had one of those types in my room before, one who pointed to various articles saying the light was harsh and bad for you, and she (Strangely it's always women who complain about the look of the light) saw my room and said it was surprisingly well lit and soothing. And I told her it was still a cfl, and all of a sudden her opinion changed, not of cfl's but that my light was giving her a headache! I tried to tell her it's all in her head and the reason my light was nice and soothing is because I have a very large diffuser, which happens to also be a hanging sculpture. The light is so diffuse that there are practically no shadows from objects more than about a foot off the ground.

The fact that you have nice evenly diffused light is a big deal. This is why I wish there were more tasteful looking linear fluorescent fixtures for home use. The linear fixtures with separate ballasts are much more efficient and reliable than CFLs with twisty tubes and self-contained balasts. It's also much easier to disperse the light from a long tube evenly throughout a room than from a CFL trying to imitate a point source.

Most typical home incandescent lighting, particularly the "recessed can every 6 inches along the ceiling" designs do a very poor job at lighting spaces evenly -- they create a lot of irritating shadows and are simply not efficient at delivering light where it is needed. IMO trying to cram CFL or even LED lighting into "retrofit" fixtures will always result in poorer results than designing a fixture from the ground up.

So my point is if cfl light were the first one's invented, how much do you think people would be complaining about how unnatural incandescent light looks, because personally I think a good cfl tint looks better than a regular incandescent, much more like daylight. And a really warm incan with a CRI of 100 doesn't look as good as a warm to cool white cfl of only around 80.

The way CRI is defined, it is only really valid to compare CRI between light sources at the SAME color temperature. CRI is measuring how "close" your spectrum is to an ideal blackbody source of the same color temperature.

I absolutely agree however that 3500k fluorescent is vastly superior (subjectively, in my case) to ~2700k stock long-life incans. The spectra from some of my hotwire flashlights at 3500k is even better, still. Unfortunately, an incan burning that hot only has a bulb life measured in double- or single-digit hours.

For those looking for efficient point-source type lighting, as an alternative to halogens, I find that the new warm white LEDs are very good. As good as CFLs at 3500k and better than CFLs at lower color temps, and with the advantage that they may be focused using reflectors for accent lighting and spot lighting -- something not possible with CFLs.

 

[jtr1962]

So my point is if cfl light were the first one's invented, how much do you think people would be complaining about how unnatural incandescent light looks, because personally I think a good cfl tint looks better than a regular incandescent, much more like daylight. And a really warm incan with a CRI of 100 doesn't look as good as a warm to cool white cfl of only around 80.

Funny you mentioned that because I never thought incandescent light looked natural or good, even when I was 5 years old. The first time I talked about lights at that age, I said something to my mom to the effect of why do light bulbs look like cocky? I liked to stay in the kitchen with its circular cool-white fluorescent simply because the tint of the light seemed closer to daylight. Needless to say, I didn't know how bad those old cool-whites were with regard to color rendering or flicker, yet I still preferred them nonetheless to "yucky" incandescent. After reading up on and trying high-CRI 5000K fluorescent linear tubes about 7 years ago (incidentally that subject caused me to find CPF), I realized that today's best fluorescents have no real disadvantages. What I fail to understand is why anyone would even want to use incandescents this day in age when fluorescents can duplicate daylight much better. And daylight really is the most natural kind of light for your eyes to see with. I liken any preference for yellowish incandescent to both an acquired taste, or to set some sort of mood since its far from an ideal light source. I personally find it absolutely horrible for seeing or distinguishing colors (that includes the warm-white CFLs made in the misguided idea of "imitating" incandescent). Besides that, incandescent has always induced me to get a horrible headache. I think the reason is my brain attempting to adjust to a color temperature outside of its auto-white balance range.

I'm also with 2xTrinity on wishing more linear fixtures were made geared towards the home. Linear tubes are superior in every way to CFLs for general lighting, and much cheaper to operate. There are far fewer instances of failed ballasts, the tubes last much longer, and you don't throw out the ballast every time you change a tube. I'm also in agreement over the dislike of recessed can lighting. I see this everywhere in new construction. For a while linear tubes were the defacto type of light used in kitchens and often baths. Who was the rocket scientist who suddenly got the idea to switch to less efficient, more poorly suited recessed incandescent can lights? Just the thought of something making as much heat as a light bulb recessed into a ceiling makes me nervous. Those things never should have passed fire codes, not to mention energy efficiency standards for new homes should apply to residential lighting same as to insulation.

 

[blasterman]

Linear tubes are superior in every way to CFLs for general lighting, and much cheaper to operate.

Along with being more efficient because there is far less strikeback caused by spiral CFLs, better ballasts and power circuits, etc.

Regardless, 3500k in a good spiral CFL or linear CFL is gorgeous when it comes to home lighting, and, IMHO, vastly superior to 2700k CFL or Incan. The light just kind of vanishes in the room with the aethestic appeal of late afternoon sun.

And a really warm incan with a CRI of 100 doesn't look as good as a warm to cool white cfl of only around 80

In most circumstances I agree with you. However, Solux halogens, when they are bounced off the ceiling, are quite stunning and have a color response that no CFL can match. They just aren't nearly as efficient.

 

[blasterman]

What I fail to understand is why anyone would even want to use incandescents this day in age when fluorescents can duplicate daylight much better

One word - dimmer (and I'm semi referring to the I.Q. of the contrator who installed recessed cans)

Recessed lighting is otherwise the worst architectural invention since the fall of the Roman Empire.

 

[2xTrinity]

One word - dimmer (and I'm semi referring to the I.Q. of the contrator who installed recessed cans)

I know tons of people who buy crazy high wattage incans (like 75W reflector lamps) and install them in all their cans every six inches, then run them all dimmed to 50% output or lower all the time. This causes the incans to run at a lower more irritating color temperature, and waste a lot more power than buying a more sensible 25-45W lamp and running it at 100%.

The desire for dimming brings me back to my point about how I wish there were household linear fluorescent fixtures. Dimming a CFL is a huge challenge because it has to be retrofit to work with a basic triac dimmers meant only for incans. On the other hand, dedicated fluorescent fixtures with dimming ballasts work quite well, better than incan dimmers in my opinion.

Dimmable fluorescents have the advantage of maintaing their efficiency as they are dimmed, and they also staying the same color as they are dimmed. Some who prefer dimming incandescents for the "candle-like" aesthetic may call that a disadvantage, but I personally can't stand dimmed incandescents. I'd much rather use a dimmed 3500k-4200k light source (like moonlight) over a <2000k dimmed incandescent (like candlelight).

 

[blasterman]

This causes the incans to run at a lower more irritating color temperature, and waste a lot more power than buying a more sensible 25-45W lamp and running it at 100%.

I just love the 'fuzzy brown' glow of a K-mart 75-watt bulb dimmed 50%, don't you? Now we know what twilight on Mars looks like

Personally I find dimmed Incans neither 'romantic' nor 'aethestic' at all.....just annoying. I use 130volt standard base halogens in place of Incans when I have to, and the higher, 3000-3100k rendition of the Halogen is at least tolerable. Last a helluva lot longer to. However, Halogen has the same problem when dimmed....the only Incan/Halogen bulb that can be dimmed without dipping into red giant Kelvin ranges are Solux (because they have higher initial kelvin temps), and for some reason they limit their bulbs to MR-16 / 12volt.


Also, nobody makes a CFL reflector housing that's semi narrow flood, and some applications just demand a narrow flood of light.

The desire for dimming brings me back to my point about how I wish there were household linear fluorescent fixtures.

They are using them...well...for commercial that is. I was in a Denny's last week, and they were using linear CFL in very reflective recessed cans, and the light quality was, IMHO, excellent for dining with superb CRI. The only reason it's not used more often for residential is the stupidity of contractors and ignorance of home owners.

Again, the main advantage for linear CFLs (I assume you are referring to these) is their ballast, which is drastically superior to grocery store variety spiral CFLs in terms of efficiency and durability. I've seen some studies that show linear CFL ballasts are as much as 25-50% more efficient per lumen compared to built in ballasts incorporated with cheaper spiral CFLs.

On the other hand, dedicated fluorescent fixtures with dimming ballasts work quite well, better than incan dimmers in my opinion.

We're talking 'very' dedicated. It takes a really good ballast to handle a 90% dimmable range with straight pin CFL. I've seen them, but this doesn't include 'Home Depot' variety dimmable CFLs. As far as I'm concerned, if you want to dim down beyind 50%, then turn off your main lights and used these things called 'LEDs', which do very well at low light levels.

Anways, my main living room light is a 48" White, photographic umbrella with four CFLs shooting up into it. The umbrella lets just enough light through to give a mild torche' effect on the ceiling while providing a large globe of direct/diffuse light. It's quite stunning, and lights up everything in the room. With all four CFls going it can light up half my house, and can be 'dimmed' down by just turning on a single CFL. After visiting a friends McMansion with arrays of annoying recessed Incans I can't wait to get home. Right now I'm trying to figure out how to build a smaller version of my Umbrella lamp for LED use.

Also, the guy above talking about full spectrum CFL must have WAY different tastes than I do. Standard big box store 'Full Spectrum' or 'Natural Light' CFLs are the nastiest things I've seen and not much good for anything other than porch or utility lights. They *are not* full spectrum, and they are as hard on the eyes as dimmed Incan, just the opposite end of the spectrum. True, full spectrum CFL or fluorescent tubes are expensive and uncommon except in some newer commercial applications. 4100k is the upper Kelvin limit for CFL in my opinion before the color rendition gets too cold.

 

[Nubo]

I guess I've got some Caveman in me. For soft evening light I'm not looking for "sunlight"; more like "firelight". A dimmed Halogen tube makes me happy. That being said, we now have just one of those. All of our other fixtures (except a couple that receive only momentary use) are fitted with various CFLs, and they're pleasant enough. When first waking, though, I find I much prefer the light from my LED lights (e.g. Nitecore). At first alarm, I turn it on low, and press snooze. At second alarm, turn to high and another "snooze". This gives me a nice feeling of dawn. I sometimes will shower with the LED as well, after which the house lights seem fine to me. This avoids the jarring effect I always got when turning on lights in the morning (even incans).