RGBA vs RGBW
- Thread starterLavaASU
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DuckJordan
Touring IATSE Member
Anything from bands to speakers to choir concerts... they're supposed to replace a par56 rig (2 red, 2 blue, 1 n/c pink, 2 purple per side)... planning to put 2-4 LED pars per side. I'm getting 2 per side for now, and adding additionals (possibly AW units) in the future.
waynehoskins
Active Member
There are some white-mixing LEDs on the market; American DJ, I think, makes one. I haven't seen any of them in action, though there's a small church nearby that has them (I helped on their audio install). I don't know that I'd trust them for theatre fronts. Maybe rock-and-roll, where frontlight is less of a big thing.
The big problems are the multiple shadows and the narrow beam angles. Not to mention all I've seen aren't profile units.
The big problems are the multiple shadows and the narrow beam angles. Not to mention all I've seen aren't profile units.
DuckJordan
Touring IATSE Member
The red teh blue and the purple are going to be your easiest colors to match, just be ready for super saturated colors, with your N/C pink in mind I'd go with the amber, it will help warm up the pink to make it more of a N/C although it will be very difficult to get a decent N/C pink out of any LED.
soundlight
Well-Known Member
For an actual stage wash, I'd stick with amber. As previously said, they'll let you warm up all your colors to match your incandescent fixtures and colors much more nicely.
That being said, on the rental side of things, I find whites to be WAY more useful. You can get a much more solid white out a fixture with a white led, and in general, it is always easy to warm up a color by adding some red.
If you can squeeze a little extra money out of your budget, take a look at the LUSTR+ units from ETC. They have 7 colors of LEDs. The color rendering from the new D40's and D60's is nothing short of phenomenal. Those units are a bit more expensive, though.
That being said, on the rental side of things, I find whites to be WAY more useful. You can get a much more solid white out a fixture with a white led, and in general, it is always easy to warm up a color by adding some red.
If you can squeeze a little extra money out of your budget, take a look at the LUSTR+ units from ETC. They have 7 colors of LEDs. The color rendering from the new D40's and D60's is nothing short of phenomenal. Those units are a bit more expensive, though.
JD
Well-Known Member
RGBA and here is why:
LED's are monochromatic devices that put out one frequency of light* and the three (R,G,B) frequencies they output for RGB are not in ideal locations of the spectrum. The color "pot-hole" is in the amber area, making a white balance hard to achieve. Having the amber LED output spike right in the middle of the dead area gives the fixtures a more pleasant and realistic apparent color balance.
*= White LEDs are actually UV LED's with phosphate inside them that produces multiple outputs that we perceive as white light. Your phosphate choices are about the same as they are for CFLs and they are all weak in the amber area.
Our eyes only perceive three colors as well, and if the center frequencies of our eyes and the frequencies of the LED's were the same, we would not need the Amber one. The same problem exists in television displays and this is why at least one manufacturer is producing RGBA displays. (A is decoded from the RGB signal.)
LED's are monochromatic devices that put out one frequency of light* and the three (R,G,B) frequencies they output for RGB are not in ideal locations of the spectrum. The color "pot-hole" is in the amber area, making a white balance hard to achieve. Having the amber LED output spike right in the middle of the dead area gives the fixtures a more pleasant and realistic apparent color balance.
*= White LEDs are actually UV LED's with phosphate inside them that produces multiple outputs that we perceive as white light. Your phosphate choices are about the same as they are for CFLs and they are all weak in the amber area.
Our eyes only perceive three colors as well, and if the center frequencies of our eyes and the frequencies of the LED's were the same, we would not need the Amber one. The same problem exists in television displays and this is why at least one manufacturer is producing RGBA displays. (A is decoded from the RGB signal.)
Definitely don't have the money for the Chroma Q...
You are correct on the current rig. Pretty saturated... I think red is R27, blues are R68 usually, and I don't remember purple. It changes a bit depending on what gels I have lying around (occasionally it becomes pink, amber, blue, red or such). Only wash/front light. We use LEDs for backlight/ uplight (backdrop/cyc depending on the gig)/ eye candy...
Well I'd second the notion of using RGBA for the can's that are typically used as saturated colors and using AW for whatever can(s) you use as clear or N/C. Who's LED's are you currently using for back/up light? Do you like them, or wish they had more power? Consider how they function and then consider how LED's will function in a front light roll.
JChenault
Well-Known Member
Some minor quibbles.
An led does not produce a single frequency, but a narrow band of frequencies. (typically around 10nm)
Our eyes have cells that respond to colored light, but the response is not narrow. Ie the red and green receptors will both fire for some frequencies of light. The issue is not the frequency of the
LED source, it is the narrowness of the frequencies output.
Budget unfortunately...
Backlight (when we do it) chauvet slimpars... not impressed with anything on these other than daisy chained power and small size.
Uplight Irradiant 1/2W battens... they work great for most shows, if needed (rarely... I think the only time we've desperately needed more power was when someone wanted up to uplight a 40' tall wall) we do a double row.
JD
Well-Known Member
Thus the "spike" chart for LED fixtures. In either case there is a hole in the A region. The other problem is on the human eye end. Eyes vary in what is perceived as R, G, or B due to genetic variation*. Wide flat spectrum light sources even when gelled are perceived with less variation then narrow band sources. This is why certain people do not find certain light sources or colors offensive, but others do. (Outside of the apathy factor.)
The closer an LED fixture can be made to have a wide and even bandwidth, the better it will be perceived, even if this only involves adding a fourth spike.
The problem with white LED's is that the phosphate colors still lack the area of spectrum that the RGB LEDs do.
*= Studies were done back in the 1960s to see the minimum perceived -color- light levels at various frequencies. The results had an interesting twist in that not only the levels change from person to person, but the center frequencies did as well. We now know that perceived color balance is different from person to person as well as race to race. In servicing video cameras, manufacturers have different alignment procedures for the Asian market then the US market. In specific, What looks white balanced to someone in Asia looks "cold" to us, and what looks balanced to us looks warm to them.
Reference- Color perception variations were taught at both Hitachi Manufacturer Training as well as Sony Manufacturer Training that I attended.
There are also variations between the sexes: http://aris.ss.uci.edu/cogsci/personnel/kjameson/SexDiff.pdf
Hard to understand why we even see red:
Nice article: http://en.wikipedia.org/wiki/Color_vision
Nice data on what LED colors are available: http://en.wikipedia.org/wiki/Light-emitting_diode
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Synchronize
Active Member
The way I usually explain it to people is, if you are looking for rich yellows, oranges, and ambers, (i.e. skin tones), then you want to go with the amber LEDs. The benifit of the white LED is that you can make pastels, and you can have true white light, which you can't do without the white LED.
I personally generally opt for the ambers because the RGB channels at 255 gets you pretty darn close to true white, and I like more saturated colors over pastels.
I personally generally opt for the ambers because the RGB channels at 255 gets you pretty darn close to true white, and I like more saturated colors over pastels.
I have a tendency to also lean more towards mixing with amber to satisfy a variety of skin tones. Having said that, white included within the RGBA allows more control of the lumen output while still allowing the designer to play with the color mix. I posted this within a thread elsewhere, but in case you haven't seen these new LED fixtures-
Introducing the Multiform HP3-90 and HP5-70 LED units - YouTube
Introducing the Multiform HP3-90 and HP5-70 LED units - YouTube
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