| [GMCnet] Restoration. LED's. How many Lumina do you need in the ceiling? [message #299814] |
Thu, 28 April 2016 12:32  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Obviously perceived “brightness” of a light fixture is a highly subjective thing. In the case of LEDs, even more so. Some take the surface emission of one LED element and multiply that by the number of LED elements to express brightness of an LED unit. If all those LEDs are on one small PC board and all pointing the same direction it seems like a lot of light. But that tells you little or nothing about how much of that potential light will actually be available to reflect off objects that cause us to perceive “brightness”. For example, take that same number of LED elements and spread them out a few inches apart along a strip and the perceived light output is very different indeed even though they both emit the same amount of light.
I measured the actual available light from the fixtures Justin sells with light from one of my PC board style units installed in an eyeball fixture with no glass or diffuser - so a bit apples and oranges but the results might be helpful. The fixtures Justin sells have a three layer diffuser and the LEDs are placed in a strip radially around the inside edge so the light coming out of the fixture is very diffused and spreads evenly through the space. The light from the PC board style units is direct down and glaring. Enough so that it is hard to look directly up into that fixture.
I used my ancient old selenium color and angle corrected GE foot candle meter and got the following at the center line of the fixture:
At 6” from the fixture, 250 foot candles for the fixture Justin sells and 300 foot candles for the direct LED
At 12” from the fixture, 50 foot candles for the fixture Justin sells and 70 foot candles for the direct LED
I had expected more difference so suspect the LED elements in the fixture Justin sells may well be individually brighter than the ones in the direct LED unit.
Things change radically as you would imagine the minute you move off the center line. The direct LEDs show a marked drop off in light while the diffused fixtures show far less drop off. When you look at the light reflecting off of the first surface the light hits, the light from the fixture Justin sells spreads out evenly over a wide area with no hot spots. The direct LED fixture shows a sharp and narrow area of reflection with little of that light moving out to illuminate adjacent areas. I find the fixture Justin sells to be a more comfortable and pleasing atmosphere than the light from the direct LEDs. If I wanted to show off the sparkle in a diamond it would be just the opposite. I would want the light falling on the diamond to be as concentrated as possible to get the most sparkle.
In my studio I experimented with a lot of different configurations of light around my cutting tools. In a studio like mine everything that can hurt you is at about the end of your arms while working. When I tried concentrated “task lighting” (like the light from the direct LEDS) I became fatigued quickly and always felt a bit uneasy as the perceived brightness of light available at the ends of my arms changed as I moved. With diffused area lighting I could work far more comfortably and felt safer. The light is always about the same no matter where my arms are. That is what I wound up with a long time back and have never found the need to change.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
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Message: 2
Date: Thu, 28 Apr 2016 14:55:25 +0200
From: Peer Oliver Schmidt
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Restoration. LED's. How many Lumina do you need
in the ceiling?
Message-ID:
Content-Type: text/plain; charset=windows-1252
Justin,
> That's spec'd.
> I don't have a meter handy but I'll try to get my hands on one at some point.
thanks. My message was a bit tongue in cheek, as I have seen multiple
LED (stripes) which were all rated identical (temperature and brightness
wise), but produced totally different output.
Would be interesting to know the real numbers.
--
Best regards
Peer Oliver Schmidt
the internet company
PGP Key ID: 0x83E1C2EA
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Restoration. LED's. How many Lumina do you need in the ceiling? [message #299816 is a reply to message #299814] |
Thu, 28 April 2016 12:53  |
Olly Schmidt
Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...
Karma: 8
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Senior Member |
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Gerald,
thanks for the details you found out.
> In my studio I experimented with a lot of different configurations of light around my cutting tools. In a studio like mine everything that can hurt you is at about the end of your arms while working. When I tried concentrated “task lighting” (like the light from the direct LEDS) I became fatigued quickly and always felt a bit uneasy as the perceived brightness of light available at the ends of my arms changed as I moved. With diffused area lighting I could work far more comfortably and felt safer. The light is always about the same no matter where my arms are. That is what I wound up with a long time back and have never found the need to change.
Your findings are probably the reason why, in Germany, working lights
must always be indirect.
One idea, if one can't get rid of the direct lighting, are the colder
LED lights. Due to there higher amount of blue light they ought to keep
you awake. Never found out how true that statement is.
--
Best regards
Peer Oliver Schmidt
the internet company
PGP Key ID: 0x83E1C2EA
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Best regards
Olly Schmidt
PGP Key ID: 0x18a9 3a1f 4196 bf22
'76a Eleganza II, VA
'73 Sequoia, SH, Germany
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