LED Light Panel Questions

sfoster

sfoster

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I was slow roasting everyone with my hot lights yesterday, they all got really tired a few hours before wrap time… I need some LEDs or something that is low heat.

But it's kind of confusing, look at this one
$240 for 900 lumens
$70 for 900 lumens

Why is there such a huge discrepancy .. just because one is marketed toward people making films? :weird: I think the second one needs a little bit of wiring work to make it a standard plug.

Also this whole "wattage equivalent" they all list.. it seems to vary wildly and have little correlation with the actual wattage the light takes.

Any thoughts or input on LED lighting ?
 
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I guess I should've posted in this in the cinematography and lighting section. Okay here is an update.

I ordered a 120W LED worklight, and I'm going to build my own from a power strip too.
I'll do tests and post results next week.
 
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The difference comes from differences in CRI values: C-something Retina Index which is a scale to indicate how close a light is to full spectrum daylight.
Cheaper LEDs are often (more) greenish, because the spectrum is weak(er) in the magenta area.
Above CRI 90 is considered high and they are more expensive.

And ofcourse, marketing plays it's part probably as well... :P
 
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WalterB said:
The difference comes from differences in CRI values: C-something Retina Index which is a scale to indicate how close a light is to full spectrum daylight.
Cheaper LEDs are often (more) greenish, because the spectrum is weak(er) in the magenta area.
Above CRI 90 is considered high and they are more expensive.

And ofcourse, marketing plays it's part probably as well... :P
Click to expand...

I thought it was color rendering index but yeah i get what you're saying.
 
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Morris said:
Some of the cheaper LEDs have a tendency of giving a greenish tinge.
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All of the cheaper LEDs tend to be green. The only film LEDs I've encountered that don't look green at all on screen are in the thousands of dollars to buy.


WalterB said:
The difference comes from differences in CRI values: C-something Retina Index which is a scale to indicate how close a light is to full spectrum daylight.
Cheaper LEDs are often (more) greenish, because the spectrum is weak(er) in the magenta area.
Above CRI 90 is considered high and they are more expensive.
Click to expand...
You mean Colour Rendering Index? ;)
You'll struggle to find a cheap LED with High CRI.
 
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So I would ask some of the more experienced people here, is the cost-cutting worth the compromise in image/color? This seems like an EXTREMELY cheap way to get a LOT of light, and if a slight green spike is the only issue, I'll grab a few from Amazon this afternoon.
 
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WhiteOpus said:
So I would ask some of the more experienced people here, is the cost-cutting worth the compromise in image/color? This seems like an EXTREMELY cheap way to get a LOT of light, and if a slight green spike is the only issue, I'll grab a few from Amazon this afternoon.
Click to expand...

It also make me wonder if a slight magenta gel would correct the tinge.
I'm going out of town this weekend so I won't be able to do my tests until next week.

Power strips all have slots on the back for screw heads, so I can easily mount them to a 2x6 strip of wood.

Now I just need to find a cheap stand for a stick of wood + pivoting head.
Any suggestions?
 
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here's my design
it's been a while since i went to school for engineering but i think this should work.

6iceub.png
 
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It also make me wonder if a slight magenta gel would correct the tinge.
Click to expand...

It could in theory. In practice, I think you'd get yourself into more trouble than its worth by pushing it the other way.

The issue isn't exactly the green (while it is a problem), the problem with the lights having such a low CRI, each light may have a slightly different color. At the level that you're working, the benefit of having more light (even with a low CRI) will outweigh the downside of shooting without lights. In other words, if the option is no lights vs using these, use them.

You can get into trouble when color grading when you're using lights with different temperatures. Just be aware of it.
 
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Sweetie said:
It could in theory. In practice, I think you'd get yourself into more trouble than its worth by pushing it the other way.

The issue isn't exactly the green (while it is a problem), the problem with the lights having such a low CRI, each light may have a slightly different color. At the level that you're working, the benefit of having more light (even with a low CRI) will outweigh the downside of shooting without lights. In other words, if the option is no lights vs using these, use them.

You can get into trouble when color grading when you're using lights with different temperatures. Just be aware of it.
Click to expand...

I am shit at color grading anyway, with a macbook and an uncalibrated monitor etc it's hopeless
 
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jax_rox said:
......
You mean Colour Rendering Index? ;)
.....
Click to expand...

sfoster said:
I thought it was color rendering index but yeah i get what you're saying.
Click to expand...

My bad.
You are both right.
I mixed it up with another acronym Dedo (the CEO of Dedo Lights) uses to test lights as well, because in the CRI test skintones are almost completely ignored. At Dedo Light they measure it against another palette as well and it has retina in the name...

Oops.

BTW: if he is in town to do a presentation: go!
 
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I was told the LED work lights I ordered had a plug.. but they just came with two wires sticking out. Not even a grounding wire.

Going to take me some extra time.

Meanwhile for the home made ones.. I think I have to make my own soft box to fit but there must be some sort of adaptor I need to buy in order to mount a swivel head on top of a light stand? I found one for cameras but the bolt seems a little too short for something like this.

I haven't bought any stands just yet. Not sure what is out there.
 
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So those LED lights I ordered had a wrong description .. they don't even work with house power at all, they're DC!

no time to buy anything else, I'm filming tomorrow.
This is what I've built - 100W of daylight balanced LED

IMG_20150603_013040.jpg


Going to paint the insides white tomorrow morning.
 
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