How to Spend New Lighting Budget

[RickR]

Im confused. If by ' a good white ' you mean a good white emitter so you can have a continuous frequency spectrum in your beam so fabric, faces, etc look good - I totally agree,

But the ColorSource PAR does not have white emitter. So how can you recommend it ?

There are many paths to the same goal. From what little I've seen of the CSpar the white is quite acceptable. (Look into the magic of lime.) I am not completely against mixed to white LEDs. I have done a few shows with all LED (x7) except some incandescent specials. The conventionals did not show as different, except maybe more amber than my default warm white color. Note that these were not major productions, and I acknowledge there is a difference between incandescent and mixed LEDs. Just as there are differences between brands of gel. If "true white" is so critical then why do we filter all the incandescents?

I will say more after getting time with CSpars and some S4s. Side by side on a small stage should be very instructive!

 

[robartsd]

Yes, the important thing to a good white is to get as even coverage of the entire visable spectrum as possible. Several emitters in saturated colors distributed across the spectrum can be mixed to produce a better white than some of the "white" emitters that have been produced. We get away with using just three primaries (in either negative or positive mixing) in large part because most people's eyes only have three different types of cones to detect color (common forms of color blindness result from a deficiency in one or more of these types of cones and a rare genetic condition gives some people an additional type of cone). Interactions between negative and positive color mixing reveals some of the limitations caused by using limited primaries.

 

[JChenault]

There are many paths to the same goal. From what little I've seen of the CSpar the white is quite acceptable. (Look into the magic of lime.) I am not completely against mixed to white LEDs. I have done a few shows with all LED (x7) except some incandescent specials. The conventionals did not show as different, except maybe more amber than my default warm white color. Note that these were not major productions, and I acknowledge there is a difference between incandescent and mixed LEDs. Just as there are differences between brands of gel. If "true white" is so critical then why do we filter all the incandescents?

I will say more after getting time with CSpars and some S4s. Side by side on a small stage should be very instructive!

My issue with color mixing LED's is that it is not a continuous spectrum. This can ( not always but usually ) cause the colors of the set designer and the costume designer to be not at all what they expected and envisioned. There are some pigment / fabric colors that just don't show up at all under a color mixing LED fixture. There are some colors that pop under a color mixing LED fixture. There was a great session on this at USITT where they were looking at fabric under LED ( x7) fixtures and Incandescent fixtures and the differences were remarkable.

The difference ( and it is profound ) in a white LED is that it is producing a continuous spectrum of color with no holes. Sure there is ( in all that I have measured ) too much blue in the spectral distribution, but I can deal with that. If you are lighting faces, or scenery - and you need to use LED's - I would urge you to think strongly about using a white LED instead of any mix of RGB, or RGBA fixtures. Would I consider using just S4( x7) LED fixtures as my sole face light. Maybe - but I would have to think about it a bit first.


In any event - please share your experience with the CSpars. Be sure to do some testing with fabric swatches on a color board.

 

[RickR]

@JChenault Have you seen the spectral distribution curves of white LEDs? (of course all brands/models vary) They are as bad as fluorescent because they too use a phosphor energy transfer process. I would not call them a continuous spectrum. For years in my architectural role I railed against just that. In many ways, like the blue spikes you mention and the notorious lack of red, the unevenness is worse than the gaps. How about the HID sources in movers? Hardly a continuous curve there either.

Of course you use your eyes. Look at set and fabric samples under the stage lights, whatever they are! I'm not a huge fan of all LED, I just know it's not the worst thing either.

 

[JChenault]

@JChenault Have you seen the spectral distribution curves of white LEDs? (of course all brands/models vary) They are as bad as fluorescent because they too use a phosphor energy transfer process. I would not call them a continuous spectrum. For years in my architectural role I railed against just that. In many ways, like the blue spikes you mention and the notorious lack of red, the unevenness is worse than the gaps. How about the HID sources in movers? Hardly a continuous curve there either.

Of course you use your eyes. Look at set and fabric samples under the stage lights, whatever they are! I'm not a huge fan of all LED, I just know it's not the worst thing either.

At USITT. Dvsdave ,Gafftaper , and I spent some time with a Sekonic meter and did look at the distribution curves for,white LEDs and did not see any terrible spikes. All,of them he a blue bump, and roles off of red a bit - but the meter showed a more or less continuous curve.

Imdont know if this is the phosphor mix, or the source LED color ( blue instead of ultraviolet ). But to my eyes it is not like bad flourescent tubes.

Re flourescent tubes. I am pretty myopic. IE thick glasses so that when I see an RGB internally mixed LED and look through the edge of my glasses it resolves into distinct colors. Same thing with magenta tells ( I yet a red and blue image ). Same thing with bad flourescent tubes looking at marks on a white board. I have not tried that trick. ( looking at a high contrast image through my coke bottle glasses ) with a white LED but I will try it and take a look.

By the way. I believe the spectral distribution from the OSRAM Kreos that occasionally appears at the top of the page was from Dvsdave's Sekonic meter


Rereading your post, I don't think,we are that far apart. My point was that a white,LED is better for lighting faces and fabrics than an RGB or ( I suspect ) an RGBL. ( red green blue lime green)