Light: point sources vs diffuse sources

[time]

Here in Oz, we can buy a CF bulb from GE called "Tiny Spiral". AFAIK, it's the smallest Compact Fluorescent on the market, designed to be a same-size replacement for 'fancy round' style incandescent bulbs.

They're nominally available in three color temperatures, but the ones I've bought have been ~4000K ("Cool White"). Color rendition looks above average to my dodgy eyes.

GE claims light output equivalent to six incandescent bulbs of similar power, or 20% more than a typical CF. Given that some CF manufacturers only claim 4x efficiency, that really translates to a 50% improvement on the cheapies that most people buy.

Are they exaggerating? I don't think so. The 11W version is conspicuously brighter than earlier 'linear' tube models from Philips and GE themselves. In fact, I booted it outside to serve as an outdoor light - IMO, it was too intense for the light fitting diffusers I have in this house, so I'm using the 8W version instead.

Despite this, the bulbs don't provide anywhere near the illumination that someone like jtr1962 would expect. I think these lamps highlight a growing problem with lighting, i.e. a trend toward point sources.

Yes, the Tiny Spirals are 'bright', but their light is emitted from a very small surface area indeed, probably half that of a fancy round at first glance, but actually smaller because it's all coming from a very thin spiral tube. Consequently, they're too bright to look at but don't necessarily light a room well enough.

Dichroic halogen lamps are a common example of this problem. Tons of lumens from a very small area creates strong shadows and glare, but IMO, poor illumination.

The future promises far, far smaller light sources: LEDs. I have a new LED torch with a single white LED; it's already 'bright' enough that it carries a warning about shining it in people's eyes! They're right though; you can easily dazzle someone, yet fail to light up a room.

This little piece of philosophy was inspired by a lighting guy who matter-of-factly pointed out that LEDs were point sources and therefore quite unsuitable for ambient lighting. I think he's right. You really want a diffused panel, preferably the entire ceiling and maybe the walls as well.

The GE Tiny Spiral sure is impressive, though ...

 

[ddrueding]

What I ended up doing in my living room was put in 12 50w halogen bulbs on a track. Even this was too bright, so now they are set to wash the walls. It provides a very nice diffused effect, but because of the loss in the walls I need even more lighting. Another 600w should do

 

[jtr1962]

You really want a diffused panel, preferably the entire ceiling and maybe the walls as well.

I agree. I've already said several times on CPF that an ideal interior lighting source would be an entire ceiling with a variable illumination level from perhaps 1 to several hundred lumens per square foot. Even at maximum intensity the panels would be no brighter than an average sky. And you would have no stupid fixtures, either (why on earth did we ever get the notion that light fixtures have to be intrusive and "pretty" anyway?). Maybe OLEDs will fill this role. The closest I can come now is to use linear fluorescent tubes. If you use enough, and distribute them throughout a room, you more or less have no shadows and no light sources too bright to look at.

Your post just reminded me of yet another reason I've long stopped using incandescents and aren't even too keen on CFLs-they create annoying shadows. And having lighting low in a room as with table lamps creates totally unnatural upwards shadows. Linear tubes on the ceiling combined with full-spectrum tubes creates an environment as close to natural light as possible these days. Hopefully we'll have something better in the future.

 

[ddrueding]

So essentially you are advocating a drop-ceiling with an even distribution of fluorescents and diffuser panels? That doesn't sound all that hard; if you can afford to lose some ceiling height.

 

[jtr1962]

So essentially you are advocating a drop-ceiling with an even distribution of fluorescents and diffuser panels? That doesn't sound all that hard; if you can afford to lose some ceiling height.

Yes, pretty much that's what I would do if I were redesigning the lighting in a room from scratch. Note though that a single 4x32W fixture in the center of the ceiling of a small room (10'x10') creates nearly as good lighting as the distributed scheme. For a larger room two or more fixtures evenly spaced would do. Of course, the drawback here is that dimmable ballasts aren't widely available so you only have one lighting level. I have a 4x32W fixture in my bedroom. Sometimes, as when I'm working on the PC or watching TV, I don't want it so bright so I use a single daylight CFL in a desklamp. A better solution would be dimming the fixture on the ceiling but finding a pair of 120 VAC dimming ballasts (I've yet to see any that work with more than 2 tubes) fairly cheap is all but impossible. Finding the special switch would be beyond impossible. These things just aren't all that common. The only time in my life I came across a dimmable fluorescent fixture was in the waiting room of the hospital my father was in during his last days. Needless to say, I had little enthusiasm for studying it then. I'm surprised I even noticed it at all in the state my mind was in at the time.

 

[Bozo]

4x32 lighting usually has two ballast. They can be put on separate switchs for a dimming effect.

Bozo :joker: