LEDs - why so blue?

F

Finster

Well-known member
I'm confused. Do all LEDs have a blue tint, and thus are not good for interviews???

Here's the deal - I need a quick light set-up solution for a shoot I have in three weeks. I will be using my 5D Mark II. I will be conducting several run-n-gun type interviews in a very formal setting (on Capital Hill in Washington D.C.).

I have a Kino Flo and some Arri lights, but based on what the client is telling me I won't even have time to plug anything in. This is new territory for me!

Soooooo, that is why I'm looking at LEDs. I am thinking the LED needs to be battery operated and bi-color. I have been considering these models ...

Comer 1800
ikan 312
Vidpro Z-96K4
Zylight Z90

I realize the 5D is good in low light. But I still want some sort of control over the lighting ... for artistic reasons (I definitely will NOT be mounting the light on top of my camera!), and in case the available light is not very good.

Suggestions?
 
BTW - if the consensus is that I really can't go wrong with any of these LEDs, then I'll probably buy the Vidpro. The Zylight Z90 seems to get really good reviews, but the price is a little too high for me. At the same time, I don't want some cheap-n-flimsy piece of junk!
 
Thanks.

He says, "Neither instrument (the two LEDs he tested) is suitable for correction to tungsten with currently available CTO gels." That's one thing I'm confused about - if I purchase a bi-color LED (Zylight or ikan), then will I still experience this green spike when dialed down to 3200K???

Or is it just when you're using a gel?
 
Leds don't have to be blue or bluish in color cast. they are blue because in that bluish color range, they usually emit the brightest in terms of lumen output. Leds do come in color varieties from a deep yellow to a deep blue as well as reds and greens and almost any color imaginable. The led light manufacturers do tend to go with the bluer tinted ones because they emit the brightest as compared with the yellower ones. For example, a led with a color temperature of 3200K will output 700 lumens for a power consumption of 10 watts BUT the same led model in a bluish 6000K and for the SAME power consumption will yield 1000 lumens and be 40% brighter. Looks better on specs (that is if they spec it honestly) and can, if needed, be gelled with a yellow/amber filter to get it down to 3200K or any other temperature with the appropriate gells in place. This is where a little clarification is needed. Anything placed in front of the leds, even clear glass will reduce the brightness somewhat. Glass perhaps the least by maybe 1% or less, hardly noticeable. Put a color correcting gell to reduce the blue from 5600K to 3200K and now you have a serious light loss in the order of 2 F stops or more. That is like dimming down the brightness by a factor of 4. That led light that says it is equivalent to a 200 watt halogen suddenly becomes equivalent to a 50 watt halogen when gelled. UNLESS they specify what beam angle AND color temperature AND the lux rating is at the standard 1 meter or 3 ft. distance, that halogen equivalent stuff is hogwash. Another issue is the beam angle of the light projected. Ever notice that all the led units that have them many tiny leds in them are on the narrow and spotty beam. That is because each and every one of them leds are encapsulated with a clear half dome "lens" on top of them, acrylic or polycarbonate material that also serves as a phosphor protector. That half dome design really "focuses" the phosphor from it's native super wide beam to a tight and bright spot, usually in the 30 to 40 degree range. To re-widen that spot up a bit for practical video use, they graciously provide the unit with a diffuser which does an excellent job of widening that beam but does an even better job of cutting down the light. Now let's say you have a light that is blue to begin with and you really need a wide 3200K beam. 2 filters needed and a huge hit on the light output. The majority of pre led era light were of the halogen warm varieties ( 2700-4000Kish) and videographers got along fine with that. Most all were of that color. If blue was needed, then a blue filter was used. Same thing could happen with leds, take a yellow and THEN change to blue if required. The yellow would have a better CRI ( color rendering index) to boot. 3200K leds and powerful ones do exist. There are available high 90CRI index 3000K SINGLE leds that output a true equivalent to a 75 watt halogen or 1200 luxes at 3 feet. They don't use them because they want you to buy the cheap green spiked ones that come a dime a dozen and made of plastic that are cookie-cutter method produced. There is more profit in them and most would rather purchase 4 of them rather that a really good single one.
 
Thanks for all that info. Very helpful.

So if I purchase a bi-color LED (the Zylight or ikan) and set the dial to 3200K, the brightness will be LESS than when the dial is set to 5600K? Or does this loss in brightness only happen when you're using gels (forgive my color temperature ignorance)?

You also mentioned the "cheap green spiked ... plastic ... cookie-cutter" LEDs. So the Litepanel 1x1 Bi-Color LED Flood Light for $2500 is considerably better in quality/brightness/color temperature verses the iKan 312 for $400? I know the Litepanel is bigger, but if I were to stack three or four iKan's side-by-side, is the Litepanel still better?
 
Interesting. I really think I'll need it to work on a battery. Looks like the CL-LED600 might work. I was thinking bi-color. However, if you're getting good skin tones with the gels ...

--------

Oops - I see that the CL-LED1200 runs on a battery, too.
 
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Thanks for the link. I'm at a coffee shop. The connection keeps cutting out on me whenever I try to watch A Strange Confession. But from what I've seen the lighting looks really great! I'll watch the whole thing when I get back home.

I've already exchanged a few emails with the coollight folks. Thanks again for the tip!
 
"So if I purchase a bi-color LED (the Zylight or ikan) and set the dial to 3200K, the brightness will be LESS than when the dial is set to 5600K? "

Most likely 99.9999999% of the times the yellow,amber tinted, warm leds will have a lower bightness output than the bluer ones. UNLESS the manufacturer factored in the compensation of underpowering the blues in order to have an equal amount of brightness on both ends.Leds are classified in brightness and color temperature known as bins or binning. The SAME led may be in several bins depending on lumen per watt and color figures as well as CRI rendition. Why led lamp manufacturers always seem to choose the bluer ones when the neutral and warm ones are readily available is beyond me. Perhaps they made a huge surplus of blues, or the fact that the warmer higher CRI ones are a wee bit more costly. A lamp that would sell for $199 with the blue ones can easily be made with the warm ones for a few dollars more. The human eye may perceive the bluer ones to be brighter even though a lumen measurement may indicate the same output on both. I myself would prefer high CRI 3200K's and worry about gelling/filtering them to color taste as the need arrises. 90% of most videographer's work is usually done with the 3200K's for indoor work. Outdoors, I use a silver reflector.
 
I don't know about other LED manufacturers but I can tell you Cool Lights manufactures both 3200K and 5600K versions of just about everything we do including LEDs. Our bi-color LED product is very popular because it gives you the choice when you may need it.

The overwhelming majority of customers today choose daylight across the board in fluorescent, CDM/HMI as well as LEDs--its not us choosing it for them. The reasons they do this are many including that many sensors on cameras today are optimized to daylight lighting. If we made more 3200K versions of LEDs than we do now, they'd sit on a shelf for quite a while longer because its not what most customers want. On the bicolor unit, from what I understand though, most customers choose to leave all LEDs on as they do prefer the daylight range and our bicolor unit is a bit different from all the others in that its tuned to give you the daylight range when all LEDs are on so you aren't missing half the output when you are using daylight as you would with all the other bicolor panels on the market. Customers told us they didn't like that about bicolor panels that they knew about (missing half the output most of the time) so we responded with something which gives them full power when they use it in the most popular mode today--daylight.
 
Thanks for the feedback everyone. I finally decided on the CL-LED600.

My first experience with LEDs. Crossing my fingers!
 
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