It used to be easy.
40 watt? 60 watt? 100 watt? tri-light?
done.
Now I spend 20 minutes at the light bulb aisle, trying to figure out what to buy, and in the end I’m not sure what I’ve got.
I want to get a tri-light with soft warm light.
The GE bulbs that I think I want are LED HD. With a colour temp of 2700 k.
What’s LED HD?
What’s a colour temp?
Is 2700 k good? bad?
It says 50 - 100 - 150. Is that equivalent to the old watts?
Help!
look at the “lumen” … that is the amout of light (about 1000lm are already pretty bright)
and IMHO shoot for 4000k (daylight) … those 2700k are “cabin with fireplace” type of warm lighting and the 6000k is somewhat of a cold sterile morgue lighting for me …
That’s exactly what I want, thanks.
Ah - I’ve found “light output” in lumens:
500 - 1,100 - 1,800
Is that an alternative way to describe brightness? equivalent to 50 - 100 -150?
Colour temp is how hot a black body would be to radiate the same apparent hue of light. There is no right answer. But 2700 is low, so is a, counter intuitively, warm light. Sunlight is considered to be 6500, and that is a very harsh, and cold light. I like about 4000 for living rooms. YMMV.
What you also want to look for is a high CRI value. Out of 100 this indicates how good the light is at making objects look the right colour.
LED lamps don’t emit a continuous range of wavelengths. So, like fluorescent lights of old, they can change the apparent colour of objects to look wrong. Better CRI, better perceived colour. HD probably is a marketing name for a better CRI.
Numbers like 50, 100 and the like are probably an attempt to line up apparent brightness with incandescent lights of old. But it won’t be perfect.
I’m not finding CRI anywhere on the box.
Just found very fine print: “Provides nearly the same light output as a 50-100-150 watt incandescent bulb (500/1100/1800 lumens vs 615/1540/2155 lumens)”
Does “k” stand for “kelvins”?
The gummint has some helpful tips for you
Lumens are to light what
- Pounds are to bananas
- Gallons are to milk
Lumens let you buy the amount of light you want. So when buying light bulbs, think lumens, not watts.
The brightness, or lumen levels, of the lights in your home may vary widely, so here’s a rule of thumb:
- To replace a 100 watt (W) incandescent bulb, look for a bulb that gives you about 1600 lumens. If you want something dimmer, go for fewer lumens; if you prefer brighter light, look for more lumens.
- Replace a 75W bulb with an energy-saving bulb that gives you about 1100 lumens
- Replace a 60W bulb with an energy-saving bulb that gives you about 800 lumens
- Replace a 40W bulb with an energy-saving bulb that gives you about 450 lumens…
As for color temperature, good ol’ incandescent light bulbs had a color temperature of roughly 3000K. That’s on the warmer end of the spectrum, and the old bulbs give of a red-tinged glow. The 2700 bulb the OP found is actually a little more reddish than traditional bulbs, closer to the cozy cabin fireplace light Al128 mentioned.
“K”, but yes
CRI (Color Rendition Index) is somewhat of an advanced concept, with leds with high CRI (they become very expensive, very fast) mostly used in specific, often technical setting e.g. medical lighting in ER’s (where correctly “reading” colour hues might be highly relevant)
not having CRI values noted on the retail box, means probably “standard-low” CRI value, as most ambient run-of-the-mill Led bulbs for domestic use will be.
Took me a minute to figure this out, but I guess a “tri-light” is what is called a “3-way bulb” in the US.
Incandescents are equivalent to 2700-2800K (though depending on wattage and dimming the actual color temperature of an incandescent light can be as low as 2400-2500K). Halogen lights are more in the 3000K range. You may not notice much difference if a room has all of one or the other, but if you have both in the same room you’d be able to tell. The “amber” Edison type bulbs that generally don’t give off much light are in the 2200K range, though there are plenty of Edison bulbs with more output and color temps in the 2700-3000K range.
Our eyes are more sensitive to blue light in darker conditions, so indoors a daylight bulb, even a 4000K one, can look quite blue and harsh especially at night. I find anything over 3000K unpleasant in a residential setting. 3500K fluorescent tubes used to be fairly common for kitchens, closets, and bathrooms, but that doesn’t appear to be a standard color temperature for LEDs which jump from 3000 to 4000 to 5000. Cooler light is fine in the basement or garage, but I don’t want it in my living spaces. Some people seem to love daylight bulbs, and I think they’re nuts.
2700K is the way to go. Everything else will look harsh if the bulb is exposed. If the bulb is inside a yellowish lampshade, maybe you could get away with 4000K.
To reproduce a regular (not workroom) incandescent, get 2700K, as @jjakucyk points out.
One bit of confusion wrt color temperature is that what is normally described as a warmer light is at a lower color temperature.
I am a big fan of the Philips Warm-Glo lights (I think they may be called something else) that decrease in color temperature (get warmer) as they are dimmed, similar to what happens with an incandescent. I always found even 2700K to be creepy when dim.
So now I need to rely on my Physics 101 class to buy lightbulbs ?!? 
Be sure to ask for them in BTUs per fortnight
Now you have choices, rather than “it just is what it is.”
On the packaging there may be a (who knows how accurately rendered) colour strip, ranging from reddish to blueish, with some temperatures indicated, so you have some idea of what you are getting. I would not necessarily describe “daylight” as harsh—it is just… white, not necessarily what you want for your sitting room. You could also go for a adjustable-colour light if you really want. Even RGB LEDs in case you ever feel like bathing the place in purple light or other arbitrary hue.
The big box store near me (rhymes with dome repo) has a display in the lightbulb aisle with 5 or 6 actual lit bulbs ranging in color temperature. This might be useful to determine what you are looking for.
mmm
I did have choices, as mentioned in the OP: 40 watt, 60 watt, 100 watt; or fluorescents.
choices on the quantity of light … but not the quality of light (temperature, CRI,…)