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#1
Old 04-04-2001, 08:09 PM
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What's the difference?

Yes, smartass, I realize that one has clear glass and the other one had frosted glass, but is there any functional difference?
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#2
Old 04-04-2001, 08:46 PM
ftg ftg is offline
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1. You don't want a clear bulb (60+ watts) anywhere close to where your eyes will likely chance upon it. The intensity of the glow of the bare filament will cause afterimages and other annoying effects. Truly unpleasant.

That's the main reason.

2. The normal light of a clear bulb tends to be yellowish. By putting the right coating inside the bulb they can change it to a little whiter (or some other) shade. Note: some loss of efficiency here.

Hence the slogan "Soft White" (tm somebody...)

So, use a clear bulb for high power lighting needs where eyes are protected by shade/distance and white coloring is not important. E.g., high above your barn door. You can use a clear bulb in a well shaded lamp, but only if the yellow is a desired effect.

Note that small 20W bulbs used in chandi..., chanda..., umm, fancy light fixtures, are sufficiently low power to not bother eyes and the yellow is probably okay to most people as it seems more candle like.

As someone over 6', I have a few choice things to say to people who put bright bare bulbs in track lighting...

FtG aka GLP
#3
Old 04-05-2001, 09:55 PM
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More specifically, the problem that frosting is supposed to fix is that light coming from a small origin is aesthetically unpleasant. It casts very distinct and sharp shadows, and to get a given amount of illumination from a smaller source requires the brightness at the surface of that source to be higher and therefore more painful to look at.
Oddly enough, sunlight is about as extreme a "small source" light as most people are going to experience. Seems to me that imitating the light source we evolved under would produce an aesthetically pleasing illumination.
#4
Old 04-05-2001, 11:17 PM
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Nope.

Quote:
Originally posted by Napier
Oddly enough, sunlight is about as extreme a "small source" light as most people are going to experience. Seems to me that imitating the light source we evolved under would produce an aesthetically pleasing illumination.
I respectfully but vehemently disagree. You are confusing a single point source with intensity.

A bare bulb's filament is a single point source. It's also relatively small in it's intensity and throw.We'll ignore 2,000 watt incandescent lamps made for movie lights, which are immense compared to most home lamps. ( In the technical world, a bulb is called a lamp). So, this small bulb throws a sharp shadow similar to daylight. The similarities end there.

Let's take a 100 watt incandescent bulb, in a room. It's unfrosted and so throws harsh light in all directions but those covered by the base of the bulb. The 100 watt filament isn't able to throw enough light to reflect much off of white or light colored surfaces. That's why even a 100 watt bulb seems somehow dim in a large room

The sun is also a single point light, but it's intensity is greater by factors I can't figure out right now. However, point here is that the intensity is such that the direct light WILL reflect off of light surfaces, therefore creating bounced light. THAT is more pleasing to the eye. And, THAT is why frosted bulbs are popular. The frosting creates a shadowless light source, eliminating harsh contrasts between light and dark areas. The eye is happier processing softer contrast information, and so we enjoy the light more than the harsh illumination of a bare filament. If I took a light meter and metered the AMOUNT of footcandles thrown off a bare filament opposed to a frosted bulb of same wattage, I'd wager a guess they are the same.

( And, if I had a bulb of each type, I'd do a typical Straight Dope Labs experiment with my old analog style Spectra Light Meter. But I don't, so I won't. ).

Napier DID touch on one good point in there. We developed on this planet living under a single KIND of light. 5600 degress Kelvin full spectrum light. If one can duplicate that kind of light, the eye and mind is MUUUUUUUUCH happier for it. Such bulbs can be purchased in most hardware or home center type stores.

Yours in Illumination,
Cartooniverse
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#5
Old 04-06-2001, 09:14 AM
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I use frosted light globes for an entirely different reason. My bedroom light has a mostly frosted glass cover over it, so the glare of clear white globes isn't a problem. However, the pattern in the cover has bunches of grapes, which, with clear globes cast magnified grape-shaped shadows on the wall. It's truly horrible.
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