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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Lighting Forum => Topic started by: Dave Guilford on January 10, 2018, 05:21:32 PM
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30w led with a 4 deg beam versus a 60w led with 8 degree beam.
Tell me what information I'm missing to determine what I want to know.
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Well, what is it that you want to know? Or as Alex Trebek would say, “Could you phrase this in the form of a question please?”.
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30w led with a 4 deg beam versus a 60w led with 8 degree beam.
Tell me what information I'm missing to determine what I want to know.
Intensity varies inversely as the square of the distance.
If you move a light twice as far away from the subject, it will be 1/4 as bright; if you move it 4X as far away, it will be 1/16 its original brightness.
A light with a beam spread of 10 degrees at a throw of 20' with cover 10 square feet, while the same light with a beam spread of 20 degrees from the same distance covers a about 49 square feet. Since the same amount of light is spread over a larger area, the intensity is much less.
A candle in complete darkness appears much brighter than a followspot in daylight, due to contrast.
The three primary colors in light are red, blue, and green.
The square law dimming curve basically states that the square of the controller setting from 1 to 10 equals the % light output. Example: a setting of 5= 25% light output and a setting of 7= 49%.
Is there anything else you would like to know?
I know this is a bit tongue in cheek, but your question was a little vaguely worded.
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I get the feeling that maybe he is taunting me about a similar stupid question that I asked here yesterday.
If so, that's OK. I am tough and can take it. It's only a discussion forum.
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I get the feeling that maybe he is taunting me about a similar stupid question that I asked here yesterday.
If that's truly the case then this thread should be deleted. There is no reason for members here to belittle or insult people because of the questions they ask. As I tell my crews, the only stupid question is the one you don't ask! That aside, the thread you started regarding the ADJ and Chauvet fixtures is completely valid. It was not a stupid question. In your case I'd vote for a wider beam angle over brightness, otherwise the stage can look a bit "spotty" since you wouldn't have an even wash. Keep asking questions though - most of us here have no trouble answering them, and others often forget that we all started at the bottom too.
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OP: You haven't defined your needs or your resource environment. I respectfully suggest that is what you are missing.
How big (or small) a pool of light do you want? What is your trim height (or length of throw)? How many instruments do you have? How many fit in the lighting position you have?
Hang one of each on the same batten, aimed straight down. Do you see the difference? The luminous intensity might be the same, as measured at the floor, but the lit areas are very different.
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Hi guys, OP here. I have no idea what the guy was talking about where I'm insulting anyone. Not the case. I'm clueless about that. Moving on...
As I mentioned in my post, which would appear brighter:
60w led with an 8 deg beam VS 30w led with 4 deg beam?
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Hi guys, OP here. I have no idea what the guy was talking about where I'm insulting anyone. Not the case. I'm clueless about that. Moving on...
As I mentioned in my post, which would appear brighter:
60w led with an 8 deg beam VS 30w led with 4 deg beam?
2 thoughts. One you didn’t ask which would be brighter originally so thats good to know. Two, wattage is power draw and not indicative of light output. So we do not have enough information to make a determination.
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As I mentioned in my post, which would appear brighter:
60w led with an 8 deg beam VS 30w led with 4 deg beam?
You never actually asked that. If you want to know which would appear brighter, you’re still probably going to need more information such as how many lumens each light source produces. If we assume the 60w source is twice as bright as the 30w source (which may not be true), the 4 degree beam will still appear brighter since the illuminated area of the 8 degree beam is nearly 4 times that of the 4 degree beam.
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Hi guys, OP here. I have no idea what the guy was talking about where I'm insulting anyone. Not the case. I'm clueless about that. Moving on...
As I mentioned in my post, which would appear brighter:
60w led with an 8 deg beam VS 30w led with 4 deg beam?
I don't think you were accused of being the insulter. The 60 v 30 question? 1) At a common spot / coverage size? 2) What is the comparitive efficiency of the LEDs? 3) Do these lights have a lumins chart?
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30w led with a 4 deg beam versus a 60w led with 8 degree beam.
Tell me what information I'm missing to determine what I want to know.
The Password® is: PHOTOMETRICS
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Those two beam specs are probably indicating a different intent.
Are you looking at aerial effects or stage lighting?
The tighter beam will probably be more effective with haze.
What are you trying to achieve? More info needed.
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Hi guys. OP here. Here's the info
Light Source: 1x 60W RGBW 4-in-1 LED
Beam Angle: 8°
Luminous Intensity:
77,372 Lux @ 1M
15,330 Lux @ 2.5M
3,747 Lux @ 5M
And the other fixture...
Light Source: 1x 30W high-output white LED
Beam Angle: 4.7°
CCT = 6500K
Luminous Intensity:
63,163 Lux @ 1M
9,480 Lux @ 2.5M
2,185 Lux @ 5M
Will there be much of a difference in brightness, do we suspect? Small stage use, approx 400 cap room. I'm pretty confident either will be acceptable. Just trying to learn.
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Yes. The 60w fixture is somewhat brighter, and certainly covers more area. How much area do you want illuminated? More is not always desirable.
Tell us about how the fixture is being deployed, and how it is being used.
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That’s an awfully small beam for a 400 cap room unless you have 40’ or higher ceilings.
For a room with a 14’ ceiling i recently had 80 degree downlight and 36 and 50 degree sides and front.
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That’s an awfully small beam for a 400 cap room unless you have 40’ or higher ceilings.
For a room with a 14’ ceiling i recently had 80 degree downlight and 36 and 50 degree sides and front.
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Ding ding ding.
Op, get out your protractor and draw out how big 4 degrees or 8 degrees are (or get out your scientific calculator and do tan(fixture angle)*throw distance to get your beam width). Both are extremely narrow. Most LED pars are around 20 degrees which is useful with a throw of at least 10’ illuminating one performer that doesn’t move much. Anything narrower than 20 degrees is a specialty fixture that I doubt will be useful to you.
In other words, both of these fixtures are probably poor choices, no matter the brightness.
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Two, wattage is power draw and not indicative of light output.
I will disagree here. For fixtures of any reasonably similar vintage, I would argue comparing power consumption is as good as any method for determining relative output between two fixtures (maybe not so good at determining absolute output), as there is so much fudge room with beam vs field definition, throw distance, and just plain lying spec sheets on cheap fixtures. Fixtures within a couple model years of each other are going to use LED emitters that have similar efficacy, so generally a 100w fixture will produce more output than a 75w fixture, though as has been said elsewhere in this thread, that’s probably one of the less important metrics. Beamwidth is where you start.
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Ding ding ding.
Op, get out your protractor and draw out how big 4 degrees or 8 degrees are (or get out your scientific calculator and do tan(fixture angle)*throw distance to get your beam width). Both are extremely narrow. Most LED pars are around 20 degrees which is useful with a throw of at least 10’ illuminating one performer that doesn’t move much. Anything narrower than 20 degrees is a specialty fixture that I doubt will be useful to you.
In other words, both of these fixtures are probably poor choices, no matter the brightness.
Maybe this will help. FYI If these are generic (Chinese fixtures) be wary of the beam angle spec. I got some very small spots spec'd at 8 deg, but were measured to be 11 deg.
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Hey guys. OP here.
How come no one will answer my question (except Mark, and thank you).
Will there's be much of a noticeable difference between the two?
Not Chinese. No need for protractor.
I'm already good on deployment and how to utilize. I'm not new to lighting nor dmx. I'm new to specs on lights.
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How come no one will answer my question (except Mark, and thank you).
Because your question, at least without context as to what you're trying to do, seems like the wrong question.
I apologize for trying to help.
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Hey guys. OP here.
How come no one will answer my question (except Mark, and thank you).
Will there's be much of a noticeable difference between the two?
Not Chinese. No need for protractor.
I'm already good on deployment and how to utilize. I'm not new to lighting nor dmx. I'm new to specs on lights.
From the numbers, the 8 deg has a lesser lux drop-off rate from one distance metric to the next. 5x reduction , then 4.1x reduction. Compared to 6.7x, then 4.3x for the 4.7 deg.
The 8 deg also seems to have a less aggressive drop-off progression.
Are the lux ratings of the 4.7 all colors + white, or just white firing?
It is hard to compare brightness of a white light to a light capable of various colors and white.
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From the numbers, the 8 deg has a lesser lux drop-off rate from one distance metric to the next. 5x reduction , then 4.1x reduction. Compared to 6.7x, then 4.3x for the 4.7 deg.
The 8 deg also seems to have a less aggressive drop-off progression.
At the risk of again not answering the OP's question, that's not how optics works. All else equal, wider beams lose brightness over distance faster than narrower beams. Either one (or both) of the spec sheets is incorrect, or they are using very different definitions of beam and/or field angle from each other, and the 8° fixture is actually narrower than the 4° fixture, at least for where most of the power goes.
Are the lux ratings of the 4.7 all colors + white, or just white firing?
It is hard to compare brightness of a white light to a light capable of various colors and white.
Indeed. Almost certainly the brightness spec is with all colors at full, which is going to be a very different color than the white only fixture. If the white-only fixture is warm white, the multi-color fixture will have to be turned down to match, also skewing the calculations.
The best way forward is a demo.
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At the risk of again not answering the OP's question, that's not how optics works. All else equal, wider beams lose brightness over distance faster than narrower beams.
It did seem counter-intuitive, but the OP wanted info based on the numbers he provided (which he trusts).
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Be skeptical of manufacturers specifications - for lighting and sound. Not every one, but it seems like a lot of specs come with a "twist" from the marketing departments. The better companies have very detailed specs and have actually measured their products, but sometimes the comparisons are still "apples vs. oranges".
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At the risk of again not answering the OP's question, that's not how optics works. All else equal, wider beams lose brightness over distance faster than narrower beams. Either one (or both) of the spec sheets is incorrect, or they are using very different definitions of beam and/or field angle from each other, and the 8° fixture is actually narrower than the 4° fixture, at least for where most of the power goes.
Indeed. Almost certainly the brightness spec is with all colors at full, which is going to be a very different color than the white only fixture. If the white-only fixture is warm white, the multi-color fixture will have to be turned down to match, also skewing the calculations.
The best way forward is a demo.
^^^This^^^
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The context doesn't matter. I'm not asking for opinions or recommendations. Just math and measurable visual perception.
Thanks for trying to try to help though :)
Seems to me that the 8 deg beam with 60w led has more lumens. How many lumens does it take for a "noticeable dofference"?
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I'm not asking for opinions or recommendations.
Actually you are. As has already been pointed out, this is not an apples to apples comparison that you're trying to make. A 4-in-1 LED is not the same as a single color LED. Why not just provide links to the products in question? Holding back details isn't going to help you or us draw any meaningful conclusions.
Seems to me that the 8 deg beam with 60w led has more lumens. How many lumens does it take for a "noticeable dofference"?
That may be true, but as others keep pointing out it isn't so simple. Have you actually used 4-in-1 LEDs before? Assuming this is a "beam" fixture, you're going to end up with 4 tightly clustered columns of RGBW light. While the total lumens might be higher, that's assuming you have all 4 colors on. These lights don't really "mix" color either. Wash fixtures tend to be a little better, but with an 8 degree beam you're not going to be washing much. My money is still on the 30w 4 degree fixture to "look" brighter. That said, I still probably wouldn't use either for a 400 person capacity room. I'm with TJ on this - I think you're asking the wrong question.
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What question do you think I should be asking?
And also, you have no idea about my application so I'm not sure why you think I'm asking anything wrong.
I appreciate the info regarding beaming. To be honest, if probably prefer the 30w spot because it uses gobo, which means hard edges. The low res photos I've seen seem to give a soft edge on the 60w beam.
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What question do you think I should be asking?
And also, you have no idea about my application so I'm not sure why you think I'm asking anything wrong.
I appreciate the info regarding beaming. To be honest, if probably prefer the 30w spot because it uses gobo, which means hard edges. The low res photos I've seen seem to give a soft edge on the 60w beam.
”Which is better? A fighter jet, a dump truck, or a submarine?”
You keep looking for a single word absolute answer when comparing two radically different light fixtures - one is a wash fixture, one is apparently a profile fixture with gobos and possibly color filters, they have totally different light sources, and totally different beam angles, not to mention contradictory spec sheets. I’m not sure how else to tell you that there isn’t a worthwhile answer to your question.
The only application I can think of where these two products would be the ones in consideration is “I want to buy a light and these are the two models I can afford.” In every other way they are so different from each other, it would be like trying to decide to use a pipe wrench or a fork for a task.
If you have more information to share you may get more out of this thread. If not, there isn’t much else to discuss.
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Can you work a deal with your dealer where you buy both, test, and return one for credit? It will cost you a little shipping expense, but you get the light you want.
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The context doesn't matter. I'm not asking for opinions or recommendations. Just math and measurable visual perception.
Thanks for trying to try to help though :)
Seems to me that the 8 deg beam with 60w led has more lumens. How many lumens does it take for a "noticeable dofference"?
With no disrespect (and a tip of the hat to Ivan Beaver), "it depends." Whether or not it is noticable is dependent on how much other light is present. The extreme example of the difference (in a pitch black venue) is that five lux is much brighter than zero lux. In other contexts (strong ambient light present), a five lux difference isn't noticable at all.
Hence the requests for more information about the intended deployment of the fixture....