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LED-How to tell the real ligthing output of led lights?How to compare lighting power?
Old 01-13-2016   #1
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LED-How to tell the real ligthing output of led lights?How to compare lighting power?

I am looking at several led light options. Obviously, one of the considerations is how much light the led panel emits.
Some companies list their products specifying out put via "lux"
Others list Watt, W.
Others use lumens...

My questions: How to measure/compare the lighting output of led lights? Is there a way to convert these numbers? All I want to know how much light these lights output so I can compare them.
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Old 01-13-2016   #2
JP Owens
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A 42 watt led is about equivalent to a 150 watt incandescent bulb. LED ratings can be confusing.

The most important number is the CRI; I don't see one for that panel.

"Nothing exists beyond the edges of the frame."
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Old 01-13-2016   #3
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Originally Posted by JP Owens View Post
A 42 watt led is about equivalent to a 150 watt incandescent bulb.
That would be little more than 300% efficiency gain - less than I'd expect between FL and incandescent. LED usually is at least twice that efficient. You might be however right where dedicated photographic or video lights are concerned, as these are rather inefficient LED applications, constrained by CRI requirements and a flicker-free DC source.

From a long time of location work I can tell you that there is no reasonably meaningful relation between Watt and Lux (or Lux and Lumen) when you compare between different lamp types and technologies. The power consumption of a given location's illumination (which usually is the only thing your clients will be aware of) is no useful information when it comes to figuring out what extra illumination to bring - you cannot avoid that extra trip to inspect the site situation.
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Old 01-14-2016   #4
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At this point it turns out there are no standards for LED lighting defined by IES (Illuminating Engineering Society), ALA (American Lighting Association) and other international organizations. Several of these institutions have agreed to develop industry-wide standards for LED lighting output. These engineering organizations and the manufacturers realize the lack of standards is detrimental to their industry.

Philips, Cooper Lighting, TCP, Toshiba, Cree and other manufacturers have individual internal standards. There is no reason to assume the specifications for one company map to another's on a one-to-one basis.

This means the answer is: there is no way to quantitatively compare LED output based on manufacturers specifications besides making your own measurements. One can make estimates using the traditional conversion factors. However each brand (LED source) could define their lux, lumen or even watt (output) measurement for LED differently. I suppose you could investigate how the individual LED manufacturers of interest compute the output specs. Then you could develop your own standards Then your conversion estimates between watts, lux and lumens would be more certain.
Basically, I mean, ah—well, let’s say that for me anyway when a photograph is interesting, it’s interesting because of the kind of photographic problem it states—which has to do with the . . . contest between content and form.
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