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ceengland7(at)gmail.com
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 Posted: Mon Aug 24, 2020 10:12 am Post subject: Fwd: MR16 halogen lamp LED replacement: sanity check |
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On 8/24/2020 11:59 AM, user9253 wrote:
| Quote: |
One statement caught my attention:
" As LED options are naturally a brighter option, the lumen count will typically be less."
That does not make sense. Isn't a lumen a unit of brightness?
This website will help to convert from halogen to LED:
https://www.rapidtables.com/calc/light/how-lumen-to-watt.html
I agree Charlie, it will take 2 or 3 of those LEDs to replace 1 halogen.
--------
Joe Gores
Yeah; that was what prompted my 'somebody's crazy' comment. Her
|
statement was the 1st time I've ever heard that LEDs can be brighter and
have lower lumens at the same time. 
Charlie
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rv8iator
Joined: 11 Apr 2006
Posts: 144
Location: Newberg, OR
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| Posted: Mon Aug 24, 2020 10:27 am Post subject: Fwd: MR16 halogen lamp LED replacement: sanity check |
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Light ratings need explicit definition as they involve a number of variables as white light is defined in five dimensions. The old watts rating along with is it a "bare bulb", a "flood" or a "spot" used to be good enough as these are all white black body radiators.
The link you provided has a conversion of radiant flux to luminous flux. The wattage on filament bulb ratings is the input power, no direct relation to radiant flux.
Lumens describe luminous flux, Simply how bright the source appears to the human eye.
Lux is unit of how much of that brightness will appear on a surface at a defined distance. One lux = 1 lumen per square meter at one meter distant from the source. 1 footcandle = one lumen per square foot at one foot distant from the source.
1 candela = one lumen per steradian. (see below)
[img]cid:ii_ke8u4wr70[/img][img]cid:ii_ke8u6du11[/img]
White LEDs are typically rated in CD (candela) or Lm (lumens) for radiant output.. They are also specified by CCT, (correlated color temperature). Roughly 5000°K = daylight, 2500°K= candle light (yellow/orange). As CCT is a one dimensional characteristic which works well for a filament source it can produce very different results for an LED which is a cold light source. The applicable color characteristic for LEDs is "chromaticity".
If all this is confusing it is because light is electromagnetic radiation and as such is multidimensional.
If anyone is interested I will provide my slide deck to my course "Intro to Illumination" course. Contact me at chris dot stone(at)a-dec dot com. (replace the "dot" with a .) to elude spammers.
.chris stone
On Mon, Aug 24, 2020 at 10:16 AM user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>
One statement caught my attention:
" As LED options are naturally a brighter option, the lumen count will typically be less."
That does not make sense. Isn't a lumen a unit of brightness?
This website will help to convert from halogen to LED:
https://www.rapidtables.com/calc/light/how-lumen-to-watt.html
I agree Charlie, it will take 2 or 3 of those LEDs to replace 1 halogen.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=497945#497945
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ceengland7(at)gmail.com
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| Posted: Mon Aug 24, 2020 2:13 pm Post subject: Fwd: MR16 halogen lamp LED replacement: sanity check |
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Hi Chris,
As testament to my weak grasp of lighting specs, I have to 're-learn' about them every time I deal with lighting issues.
However, that salesperson's contention that LEDs are brighter, and therefor have lower lumen ratings for the same light level, makes no sense whatsoever to me. According to the interwebs, the definition of 'lumen' is:
the central cavity of a tubular or other hollow structure in an organism or cell.
"the stomach empties food into the lumen of the small intestine"
No, wait...Let's try this one:
the SI unit of luminous flux, equal to the amount of light emitted per second in a unit solid angle of one steradian from a uniform source of one candela.
So when is a lumen not a lumen? Unless that company is selling small intestines, they are feeding us the output of small intestines.
*That* was the reason for my post. They are certainly not alone in misleading claims; early on it was very rare to find a home LED bulb that truly had light output equal to its 'equivalent' incandescent or halogen version. Things are a bit better now, but too often, still not truly equivalent.
I obviously want to use LEDs; I just want honesty in their ratings just like I want honesty in ratings for any other product.
I'd love to have your presentation on lighting; it would be nice to have a reference document when I need to 're-learn' lighting from time to time. If you're going to send it to Bob, I can download it from the AEC site, so you won't have to send to multiple destinations.
Thanks!
Charlie
On 8/24/2020 1:22 PM, Christopher Cee Stone wrote:
| Quote: | Light ratings need explicit definition as they involve a number of variables as white light is defined in five dimensions. The old watts rating along with is it a "bare bulb", a "flood" or a "spot" used to be good enough as these are all white black body radiators.
The link you provided has a conversion of radiant flux to luminous flux. The wattage on filament bulb ratings is the input power, no direct relation to radiant flux.
Lumens describe luminous flux, Simply how bright the source appears to the human eye.
Lux is unit of how much of that brightness will appear on a surface at a defined distance. One lux = 1 lumen per square meter at one meter distant from the source. 1 footcandle = one lumen per square foot at one foot distant from the source.
1 candela = one lumen per steradian. (see below)
[img]cid:part1.599BE7D6.D2076DA8(at)gmail.com[/img][img]cid:part2.9BDA031F.B394058E(at)gmail.com[/img]
White LEDs are typically rated in CD (candela) or Lm (lumens) for radiant output.. They are also specified by CCT, (correlated color temperature). Roughly 5000°K = daylight, 2500°K= candle light (yellow/orange). As CCT is a one dimensional characteristic which works well for a filament source it can produce very different results for an LED which is a cold light source. The applicable color characteristic for LEDs is "chromaticity".
If all this is confusing it is because light is electromagnetic radiation and as such is multidimensional.
If anyone is interested I will provide my slide deck to my course "Intro to Illumination" course. Contact me at chris dot stone(at)a-dec dot com. (replace the "dot" with a .) to elude spammers.
.chris stone
On Mon, Aug 24, 2020 at 10:16 AM user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:
|
 Virus-free. www.avast.com [url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2] [/url]
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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| Description: |
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| Filesize: |
237.12 KB |
| Viewed: |
1464 Time(s) |
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| Filesize: |
104.13 KB |
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1464 Time(s) |
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rv8iator
Joined: 11 Apr 2006
Posts: 144
Location: Newberg, OR
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| Posted: Mon Aug 24, 2020 2:35 pm Post subject: Fwd: MR16 halogen lamp LED replacement: sanity check |
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Charlie et al...
I did see the magical art of illumination put forth by the inhabitant of
1000bulbs.com, or was it bulbs.com. I have had similar discussions with
the sales associate at superbrightleds.com In fairness it's a subject that
is a bit more complex than meets the eye. (no pun intended)
.chris
On Mon, Aug 24, 2020 at 3:21 PM Charlie England <ceengland7(at)gmail.com>
wrote:
[quote] Hi Chris,
As testament to my weak grasp of lighting specs, I have to 're-learn'
about them every time I deal with lighting issues.
However, that salesperson's contention that LEDs are brighter, and
therefor have lower lumen ratings for the same light level, makes no sense
whatsoever to me. According to the interwebs, the definition of 'lumen' is:
the central cavity of a tubular or other hollow structure in an organism
or cell.
"the stomach empties food into the lumen of the small intestine"
No, wait...Let's try this one:
the SI unit of luminous flux, equal to the amount of light emitted per
second in a unit solid angle of one steradian from a uniform source of one
candela.
So when is a lumen not a lumen? Unless that company is selling small
intestines, they are feeding us the output of small intestines.
*That* was the reason for my post. They are certainly not alone in
misleading claims; early on it was very rare to find a home LED bulb that
truly had light output equal to its 'equivalent' incandescent or halogen
version. Things are a bit better now, but too often, still not truly
equivalent.
I obviously want to use LEDs; I just want honesty in their ratings just
like I want honesty in ratings for any other product.
I'd love to have your presentation on lighting; it would be nice to have a
reference document when I need to 're-learn' lighting from time to time. If
you're going to send it to Bob, I can download it from the AEC site, so you
won't have to send to multiple destinations.
Thanks!
Charlie
On 8/24/2020 1:22 PM, Christopher Cee Stone wrote:
Light ratings need explicit definition as they involve a number of
variables as white light is defined in five dimensions. The old watts
rating along with is it a "bare bulb", a "flood" or a "spot" used to be
good enough as these are all white black body radiators.
The link you provided has a conversion of radiant flux to luminous flux.
The wattage on filament bulb ratings is the input power, no direct relation
to radiant flux.
Lumens describe luminous flux, Simply how bright the source appears to
the human eye.
Lux is unit of how much of that brightness will appear on a surface at a
defined distance. One lux = 1 lumen per square meter at one meter distant
from the source. 1 footcandle = one lumen per square foot at one foot
distant from the source.
1 candela = one lumen per steradian. (see below)
[image: image.png][image: image.png]
White LEDs are typically rated in CD (candela) or Lm (lumens) for
radiant output.. They are also specified by CCT, (correlated color
temperature). Roughly 5000°K = daylight, 2500°K= candle light
(yellow/orange). As CCT is a one dimensional characteristic which works
well for a filament source it can produce very different results for an LED
which is a cold light source. The applicable color characteristic for LEDs
is "chromaticity".
If all this is confusing it is because light is electromagnetic radiation
and as such is multidimensional.
If anyone is interested I will provide my slide deck to my course "Intro
to Illumination" course. Contact me at chris dot stone(at)a-dec dot com.
(replace the "dot" with a .) to elude spammers.
.chris stone
On Mon, Aug 24, 2020 at 10:16 AM user9253 <fransew(at)gmail.com> wrote:
>
>
> One statement caught my attention:
> " As LED options are naturally a brighter option, the lumen count will
> typically be less."
> That does not make sense. Isn't a lumen a unit of brightness?
> This website will help to convert from halogen to LED:
> https://www.rapidtables.com/calc/light/how-lumen-to-watt.html
> I agree Charlie, it will take 2 or 3 of those LEDs to replace 1 halogen
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
_________________
C. Stone (RV8iator) |
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