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Looking For A Reading Light
Shouldn’t I be able to replace a 100 watt light bulb here with some LED luminaire, getting better light at one fifth the cost?
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Looking For A Reading Light
At November 3013, I tried this first, a “flood” light sold purchased at Home Depot, in March, 2013, cost $24.97. I bought a package already hacked open, intending I would return it after some tests. By the pound, it was a pretty good deal, though, and I kept it as lab stock. In time, I cut the glue strips, and detached the plastic cap, to see the remarkable workmanship of a rather useless light, Package labeling, too, is an open issue. The claim of equivalence to a 75 watt point-source incandescent light bulb is unambiguous, and absurd. At directional 800 lumens, it gives task illumination at: 800/450 * B4 = B7 It is more like a 150 watt light bulb. Screwed into the desk lamp, I do find that 50% improvement of brightness, staying cool. But, the lamp topples with great determination.
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Looking For A Reading Light
Try then, this much-lighter new version, 650 lumens, 11.5 watts, which will be a bit brighter than a B4 100 watt bulb. For Brightness Number, divide directional lumens by 450. 650/450 * B4 = B5.8 This is at same 57 lumens per watt technology as its heavy predecessor.
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Looking For A Reading Light
Now the lamp is nearly able to stay upright. But it looks weird.
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Looking For A Reading Light
B A
C
D
A is Ecosmart “65 watt” LED Flood, first version. B is Ecosmart “65 watt” LED Flood, improved C is 100 watt incandescent D is “60 watt equivalent” Utilitech LED Pro, USDOE “L Prize” Weigh the specimens: A = 429.2 g with lens B = 145.2 g C = 27.5 g D = 247.3 g
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Looking For A Reading Light
B
C
D
Brightness differences can’t be determined by individual photos of a reading task, where a no-flash camera adjusts each time to available light, but I tried. Judge by best camera ability to focus, crispness of text in photo. B, the new Ecosmart 2700°K LED “65 watt,” is the loser. D, the Utilitech LPrize “60 watt” LED bulb is best in this, though perhaps 60% dimmer than C, a 100 watt incandescent bulb. I think mult-faceted light gives more clues for camera focus, and there is a lesson in that. A room should have many smaller lights, rather than a single big one. And, let one or more of the little overhead lights be where needed for reading.
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Looking For A Reading Light
For brightness comparison, mount the 2700°K Ecosmart “65w” on the right, a 2700°K 4” Glimpse at left. Brightness comparisons do not require that a luminaire be compatible with a desk lamp, in this imagining of reading lights. Do choose same color temperature for comparisons.
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Looking For A Reading Light
4” Glimpse 2700°K, 9.5 watts 425 lumens, B3.8 44.7 lumens/watt
Ecosmart “65w”, 2700°K, 15 watts 650 lumens, B5.8 43 lumens/watt
Stated lumens match the visual result. The 425 lumens Glimpse is 425/450*B4 = B3.8. The 650 lumens Ecosmart “65w” LED flood is 650/450*B4 = B5.8.
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Looking For A Reading Light
4” Glimpse 2700°K, 9.5 watts 425 lumens, B3.8 44.7 lumens/watt
100 watt incandescent 1600 lumens, B4 16 lumens/watt
The 2700°K Glimpse gives slightly better illumination in this comparison. Color temperature of the 100 watt incandescent is seen to be higher, perhaps 3000°K. I‘m surprised. Is color temperature less than 3000°K more illuminating to the human eye, and to a human-calibrated digital camera? Once again, it is confirmed that a 100 watt incandescent bulb, now banned and hard to find, is matched in delivered practical illumination, by a 450 lumens directional LED of broad beam angle greater than 90°.
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Looking For A Reading Light
Utilitech A19 LED Bulb 800 lumens, 13.5 watts 3000°K, dimmable 59 lumens/watt B2.4
T91 LED 750 lumens, 14.5 watts 3000°K, dimmable 51.7 lumens/watt B6.7
With a directional LED lighting reference, 450 lumens defined B4, now assess another reading light candidate, an L-Prize bulb offered by Utilitech. The L-Prize aimed to create an LED point-source bulb equalling the illumination of a 60 watt incandescent bulb. The T91 is brighter here, by more than times-two. With nearly-equal lumens, the difference is entirely the result of adverse arrangement of LED elements in the L-Prize bulb.
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Looking For A Reading Light
Utilitech A19 LED Bulb 800 lumens, 13.5 watts 3000°K, dimmable 59 lumens/watt B2.4
4” Glimpse 450 lumens, 9.5 watts 3000°K, dimmable 47 lumens/watt B4
In a direct B4 comparison, the L-Prize bulb clearly is less than B4 in end-on task illumination. Surely it is no brighter beaming to the side all-around. Estimate L-Prize brightness as 60/100*B4, B2.4.
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Looking For A Reading Light
Utilitech Pro LED A19, #0338931 800 lumens, 13.5 W, 3000°K
Could there be any good purpose for this silly , fragile and expensive invention?
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