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Author Topic: School me on lights  (Read 1295 times)

David Allred

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Re: School me on lights
« Reply #20 on: January 16, 2018, 09:11:15 am »

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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TJ (Tom) Cornish

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Re: School me on lights
« Reply #21 on: January 16, 2018, 09:49:04 am »

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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David Allred

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Re: School me on lights
« Reply #22 on: January 16, 2018, 10:22:19 am »

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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Don T. Williams

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Re: School me on lights
« Reply #23 on: January 16, 2018, 01:40:34 pm »

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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Tim McCulloch

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Re: School me on lights
« Reply #24 on: January 16, 2018, 02:19:46 pm »

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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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Dave Guilford

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Re: School me on lights
« Reply #25 on: January 16, 2018, 05:05:28 pm »

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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Jeff Lelko

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Re: School me on lights
« Reply #26 on: January 16, 2018, 06:02:58 pm »

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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Dave Guilford

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Re: School me on lights
« Reply #27 on: January 16, 2018, 08:25:27 pm »

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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TJ (Tom) Cornish

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Re: School me on lights
« Reply #28 on: January 16, 2018, 10:28:13 pm »

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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David Allred

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Re: School me on lights
« Reply #29 on: January 17, 2018, 07:32:23 am »

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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