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Author Topic: School me on lights  (Read 2602 times)

Dave Guilford

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School me on lights
« on: January 10, 2018, 05:21:32 pm »

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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Jeff Lelko

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Re: School me on lights
« Reply #1 on: January 10, 2018, 06:53:08 pm »

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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Scott Hofmann

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Re: School me on lights
« Reply #2 on: January 10, 2018, 08:29:43 pm »

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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Scott Hofmann

Gordon Brinton

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Re: School me on lights
« Reply #3 on: January 10, 2018, 08:30:44 pm »

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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Jeff Lelko

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Re: School me on lights
« Reply #4 on: January 11, 2018, 03:45:29 pm »

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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Mark Cadwallader

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Re: School me on lights
« Reply #5 on: January 11, 2018, 04:40:59 pm »

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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Dave Guilford

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Re: School me on lights
« Reply #6 on: January 14, 2018, 08:06:12 pm »

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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Cailen Waddell

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School me on lights
« Reply #7 on: January 14, 2018, 08:37:32 pm »

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. 


Sent from my iPhone using Tapatalk
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Jeff Lelko

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Re: School me on lights
« Reply #8 on: January 14, 2018, 08:40:30 pm »

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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David Allred

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Re: School me on lights
« Reply #9 on: January 14, 2018, 08:43:52 pm »

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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