LED Stage lighting

LED stage lighting is not new - I've been seeing them for over a couple years now - but they are getting into the mainstream where some major venues are now using them.

The typical unit resembles old school incandescent spot light housings -



this is at a well known club and they are not used for trivial lighting - they are in fact the main bank of front stage lights - shown in this shot from behind the stage -



A major concert venue has been using LED stage lighting for over a year now - as shown here - it's pretty obvious there is a bank/row of LED lights -




However, the other night I noticed that a smaller club had a different non-conventional set up -



this seemed to also work quite well

I've set some dance floors up with LED Pars and agree the 1 and 3 watt based versions are exceptionally versatile and fun to play with. With a DMX controller and several of them slaved the color palette is amazing, vivid, and has flexibility you just don't have with HID or halogen.

Only disadvantage with LED pars is they don't project a very intense white compared to HID, and they don't project a very sharp light cone but instead is fuzzy and flood-ish.

I'm not a fan of the light bars you have posted at the bottom. They are just bright and don't do much.

Actually my main complaint about LED stage lighting is actually light-persons seem to be infatuated with them, and keep changing colors for change's sake - also the venues I go to seemed to like mixing blue with red to get overall magenta hue - which does not seem come out that well in photographs.

There is also one other aspect - with LEDs - the colors are pretty "pure" or at least peaks more sharply on the red, green and blue wavelengths - this also causes some problems with white balance such that the photos do not look like the the scene as the eyes see it. Using fixed daylight white balance may seem the right balance to use - but if there are any incandescent being used - those would then thrown the balance off - using tungsten balance certainly does not work at all -
there is a problem with AWB too -

The "white" (ie: Red Green Blue LEDs all on) when contrasted with any incandescent back lighting seems to fool most AWB (Auto White Balance) into giving a picture that's just way too blue.

Agreed on all accounts. The good thing though is that we're seeing a demise of the nasty 5mm / 10mm PARs which for the most part are garbage. I got a bunch of JamStars for free a couple of years ago and already half the blue 10mm LEDs are dead. I really want to build a very narrow angle par with less than 10 degree optics, but this doesn't seem possible in a RGB format.

Yeah, one good thing about classic halogen / HID PARs is you didn't have 16.7 million colors available for the road techie to color cycle through in 10 seconds

As for color balance, only thing I can tell you is shoot RAW and try to balance off the performers faces. And thank the fact you aren't shooting film and relying on me to color balance it like I used to do

blasterman said:

Yeah, one good thing about classic halogen / HID PARs is you didn't have 16.7 million colors available for the road techie to color cycle through in 10 seconds

As for color balance, only thing I can tell you is shoot RAW and try to balance off the performers faces. And thank the fact you aren't shooting film and relying on me to color balance it like I used to do

Click to expand...

The RAW advice is right on for correcting or balancing for the face.

As for lighting persons - there are very few (at least in music) who actually care or model for the performer/face - seems they are more interested in the overall (psychedelic?) effect - which in itself is not such a bad thing - after all it is a rock/musical event - I have often got great overall stage shots because of that -
but focus on an individual -
often the lights change just when I am about to take the shot(!) -
so not only do I have to wait for the expression/pose -
I also have to work out and wait for the light changing sequence too!

However there are a few who do model the performer well -


all the way back from 2000 (obviously only standard incands used) -
on a 2Mp Canon PowerShot S100 the original Digital ELPH.....

from 2009

same lighting person - different venues
and the 2009 uses some LED PARs

I also had the occasion to shoot at a theater stage -
and could tell straightaway that the lighting was just so much better -



set up -



I don't think any LED PARs were used -
but was surprised to see fluorescents?

Nice shots BTW - look like smaller venues as well, which are certainly more fun to attend and shoot.

Wildest light show I've seen lately is for Trans Siberian Orchestra.

I've become aware of some problems with LED stage lighting in photography -

Basically LED lighting mix Red, Green and Blue LEDs to get almost any color.

White for example is RGB in equal proportions.

There is a tendency to use blue and red LEDs to get magenta - which is attractive and quite flattering - so it is more and more popular.

Although the combination is magenta to our eyes - it is in reality made up with red and blue light -
this makes a difference to photography/cameras -
as the resultant light is actually red and blue and pretty narrow wavelength/spectrum band too.

This makes any white balance very difficult in-camera or post-processing since the light really only has red and blue components (and little or no green) - shooting RAW unfortunately does not help since the original image lacks green in the spectrum - so it is almost impossible to get a white balance to get correct flesh/skin tones.

Not only that red and blue and very difficult for JPG to store/display -
so one loses details in those magenta areas -
so what may have looked sharp in the image when saved to JPG could end up looking soft or even seemingly out of focus.

here's an illustration:

this is with my normal post-processing/sharpening and JPG quality level -
it looks soft and even out of focus.

This is what I did to mitigate the loss of definition due to JPG compression -

this is over-sharpened by two steps over my normal - in the editor it looks very over sharpened - but when saved it is only slightly over-sharpened - one step over normal would still look soft....

I could preserve more definition by saving at a lower JPG compression too - but the file sizes are larger:

this is at 100% best JPG quality in my usual editor -
it is not that much improvement - and the file is now 124Kb vs. the 23Kb of the normally saved or 34Kb of the over-sharpened (which looks better albeit slightly over-sharp)


this is processed in PS Elements 7.0 -
where I did everything I know how to preserve the details -
resize bicubic sharpen, and enhance sharp eliminating lens blur - then saved at level 10 Max quality JPG resulting in a file that's 106Kb -
this actually looks pretty good.

I have found PS Elements 7.0 seems to do slightly better in its JPG compression is preserving details in red - but it is not that much better if one looks at the higher compression JPGs -

this is the same PSE 7.0 processed pic saved at level 4 quality and file size 24Kb roughly the same size as the first image posted. It is slightly better but still looks unacceptably soft.

There is also a double whammy sometimes with some sites like Picasaweb and some forums where lower compression larger filed JPGs are actually further compressed by the site resulting in softer looking images.

So even if one saves to a lower compression/larger file the site may re-compress the displayed image to show it soft.

That's why I ended up doing the over-sharpening of my images and saving to a higher compression JPG for a smaller file -
so that hopefully sites will not further compress my images.

The reason why magenta looks so soft, is because most cameras use a Bayer sensor arrangement, which gives half the available resolution to green pixels, and then splits the remaining half between red and blue.

You can see the difference by shooting a relatively neutral, detailed scene, and then looking at each channel as an independent monochrome image in Photoshop; the red and blue channels will be visibly softer than the green.

As a result, your red and blue channels are given short shrift right off the bat, and you will see this effect even with RAW.

It just gets worse from there if you shoot JPEG, since it compresses red and blue "harder" than green, since green is the biggest contributor to luminance. Shooting RAW at least avoids this second stage of loss.

The Foveon sensor is supposedly a true RGB sensor, and so its RAW files might be equally sharp in all channels, but I don't own one and cannot confirm it.

One other things: since red and blue are at opposite ends of the visible spectrum, any chromatic aberration (CA) present in your optical system will be at its worst in magenta scenes.... including when that optical system is the human eye.

Canuke said:

The reason why magenta looks so soft, is because most cameras use a Bayer sensor arrangement, which gives half the available resolution to green pixels, and then splits the remaining half between red and blue.

Click to expand...

Thank you very much for the very succinct and well written summary.

You expressed what I was trying to illustrate very well.

The other point I should emphasis - with older tungsten halogen lighting even when filtered/gel -
still produces lighting that has a broader more continuous spectrum
whereas with LEDs - the spectrum is discontinuous with peaks at red green and blue -
it's our eyes that are "fooled' into seeing the combination colors -
unfortunately the camera is not fooled - hence the difficulty in photographs.

Also JPGs are so ubiquitous and almost mandatory for any photo to be displayed on the web - even if one shoots RAW - the result has to be in JPG where the detail losses become inevitable - saving to lower compression/larger files does help - but then we may face the double-whammy of sites that compress larger files - my work-around is to over-sharpen the image and save to the same normal higher compression JPG - which seems to work - but still not ideal -
however what the camera has not captured in the first place cannot be transformed back to an ideal photo.

Thank you.

I take a lot of concert pics but I junk a lot of them because the stage lighting isn't ideal. Opening acts often just get some red lights and no spot light- this makes the headliner appear so much more colorful.

I always shoot in RAW mode because I feel that it allows me to manage my really good shots the way I want much better than JPEG.

greenlight said:

Opening acts often just get some red lights and no spot light- this makes the headliner appear so much more colorful.
I always shoot in RAW mode because I feel that it allows me to manage my really good shots the way I want much better than JPEG.

Click to expand...

Yes, I've noticed that as well - opening acts tend to get less than ideal lighting.

But the shots I posted were of the main attraction -
my point was with LED stage lighting - there appears to be a trend to magenta (using only red and blue LEDs)
which looks good by eye - but are a real bear for photography.

Because LED lighting has a narrow and discontinuous spectrum there is difficulty in getting any semblance of white balance control.

The generic advice appears to be to use RAW - as if that could control the discontinuous spectrum -
RAW canNOT do much better either, when the lighting severely lacks green in the spectrum as in LED lighting.

Finally, as mentioned, to be able to display the image, even when shot in RAW - one has to save to JPG -
which has all the attendant compression problems in red components -
unfortunately one just cannot get away from that either.

Canuke said:

One other things: since red and blue are at opposite ends of the visible spectrum, any chromatic aberration (CA) present in your optical system will be at its worst in magenta scenes.... including when that optical system is the human eye.

Click to expand...

This is also a very good point -
plus as some have pointed out red and blue being at the opposite ends of the spectrum so there is a bath tub void in the middle frequencies of light - auto-focus systems tend to have difficulties as well - even resorting to manual focusing - our eyes as you point out have difficulties.

All-in-all magenta made up with red and blue LED lights may look good, but pose real difficulties for photography......

However neither chromatic aberration nor focusing were the problems in the samples posted -

Details:

over-sharpened by 2 steps (1 step = PSE 7.0 Adjust Sharpness 100%, 1 pixel, remove Lens Blur)
left is saved to quality 4 my usual size (32Kb) - right is to quality 8 much bigger file size (76Kb) to show over sharpening

This clearly shows that the main subject is very well in focus and has good definition/details -
loss of details in the other samples posted - of this exact same shot - was due to JPG compression -
What I did to mitigate the loss of definition in JPG compression - over-sharpened by two steps over my normal - in the editor it looks very over sharpened - but when saved it is only slightly over-sharpened.

This was shot with a humble Pentax 18-55mm (Mk 1) kit zoom lens.

Pentax K-x - ISO4000, f/4.5, 1/60, 45mm

Canuke said:

The reason why magenta looks so soft, is because most cameras use a Bayer sensor arrangement, which gives half the available resolution to green pixels, and then splits the remaining half between red and blue.

Click to expand...

The chromatic limits of a Bayer arrangement have nothing to do with the posted images. This has topic has been beat to death on Dpreview, and the common way to show Bayer limits is with sharp patterns of red-black-red-black, etc. This tends to trip up very high rez bayer sensors but not so the Foveons. Essentially it only matters when shooting test patterns, or some specific cloth patterns, and involves some pretty extreme pixel peeping. It doesn't matter with skin tones.

RAW canNOT do much better either

Click to expand...

Bull. RAW would at least stop the channels from clipping and allow the image to be adjusted so it looks like it was taken under theatrical lighting and not like inks ran out in the press.

Not shooting RAW is the reason there isn't any lattitude with color adjustment.

blasterman said:

Bull. RAW would at least stop the channels from clipping and allow the image to be adjusted so it looks like it was taken under theatrical lighting and not like inks ran out in the press.

Not shooting RAW is the reason there isn't any lattitude with color adjustment.

Click to expand...

Can you please explain how to recover to a natural colored balance as in the case of magenta using only red and blue LEDs which have very narrow bandwidth so produces a void in the middle of the spectrum?

I've tried shooting paired RAW and JPG and I cannot seem to get to a real flesh tone.

You won't get a natural flesh tone.

However, RAW will allow you to at least get some tonal spacing and depth so your images don't look like cartoon characters. Again, I assume you want you images to look like theatrical lighting.

Also, JPG modes typically limit themselves to sRGB, and this also contributes to channel clipping under extreme color ranges. Shooting RAW with AdobeRGB and then converting to sRGB takes the sting out of this.

I have RGB PARs and can easily replicate the monochrome lighting you are working under, however, I know what to expect, and results won't be that harsh. Given my camera is much older we wouldn't be able to draw a conclusion then because our workflows and hardware are so different.

My advice would be to start with a dedicated forum like the Pentax forum on Dpreview because we might be talking about camera functionality here.

blasterman said:

You won't get a natural flesh tone.

Click to expand...

Thanks for that -

I do realize the greater flexibility and technical superiority of RAW -
but the point I was trying to make was that with extreme lighting like red and blue LEDs making magenta causes havoc with photos that even RAW would have a difficult time with.

Believe me I tried with RAW to get some semblance of flesh tones -
and you probably already the know the answer -
I obviously could not get anywhere near flesh tones -
that was the only point I was trying to make re: RAW....

However -

blasterman said:

However, RAW will allow you to at least get some tonal spacing and depth so your images don't look like cartoon characters. Again, I assume you want you images to look like theatrical lighting.

Also, JPG modes typically limit themselves to sRGB, and this also contributes to channel clipping under extreme color ranges. Shooting RAW with AdobeRGB and then converting to sRGB takes the sting out of this.

I have RGB PARs and can easily replicate the monochrome lighting you are working under, however, I know what to expect, and results won't be that harsh. Given my camera is much older we wouldn't be able to draw a conclusion then because our workflows and hardware are so different.

My advice would be to start with a dedicated forum like the Pentax forum on Dpreview because we might be talking about camera functionality here.

Click to expand...

I appreciate this advice.

UnknownVT said:

The generic advice appears to be to use RAW - as if that could control the discontinuous spectrum -
RAW canNOT do much better either, when the lighting severely lacks green in the spectrum as in LED lighting.

Click to expand...

Since Blasterman prompted me - I experimented some more and am almost about to eat my own word about RAW -

I have this shot that I took in paired DNG and JPG -

which has the magenta (red and blue LEDs only problem)
the outlines shows the areas I concentrated on.

First I used ACR 5.6 (Adobe Camera RAW) in PhotoShop Elements 7.0
(note: ACR 5.6 is the latest version which supports the Pentax K-x)


Left: As Shot settings ............................................ Right: set White Point on the shirt.


Left: As shot settings ............................................. Right: set White point on shirt of bassist as previous sample.

One can see even with "manual" white point selection there isn't that great an improvement and this is with ACR 5.6 the latest version that officially supports the Pentax K-x.

This is why I said RAW couldn't do that much better in recovering skin tones in such extreme lighting.

But I thought I'd play around with Pentax Digital Camera Utility 4.11 (based on SilkyPix)
and I was surprised by the results -


Left: Camera Settings .............................................. Right: set Grey Point on bassist shirt.

WoW! I didn't think this was possible, since I thought the main subjects lit with mainly red and blue LEDs would lack anything in the middle of the spectrum, and especially since ACR didn't improve things that much.

Harder test was the drummer -

Left: Camera Settings .............................................. Right: Grey Point on bassist shirt as sample above.
No this does not show any great quality -
but I am really impressed in the ability to get something that even resembles skin tone here.

Not that I really want to present realistic flesh tones in a shot such as this - but I am really surprised that the Pentax Digital Camera Utility/SilkyPix (4.11) can actually manage even this much.

Here's the overall shot that was balanced by Pentax DCU/SilkyPix -

straightforward adjustment to brightness contrast and a bit of sharpening but I had to "deselect" the bassist's shirt to bring up the brightness in the rest of the pic

What's happening with RAW here is you are actually replacing one color with another, but because RAW is working with the full, unaltered camera capture it's able to wiggle out the extra working lattitude and keep things sane. I used to have to do this with film and commercial lab gear, and I don't even want to start.

I realize you are working at very high ISO's, and other than perhaps a D3 this is very hard on the camera processing. At lower ISOs you might have more wiggle room with JPG. At higher ISOs there's far less data to work with, so this results in the cliping and harsh contrast.

Plus, after doing some research it appears that your Pentax has some minor issues with head-room / contrast. Coupled with the conditions above this was why you were having such a hard time with JPG. All the shots are awesome though, and I hope this will give you some tools to have better control.

blasterman said:

What's happening with RAW here is you are actually replacing one color with another, but because RAW is working with the full, unaltered camera capture it's able to wiggle out the extra working lattitude and keep things sane.

I hope this will give you some tools to have better control.

Click to expand...

Thank you for your advice and encouragement.

However I still have the quandary of presenting a magenta (made up from red and blue LEDs) as-is - that is even when shooting in RAW - as can be seen in the "As Shot" and "Camera Settings" samples from ACR and Pentax DCU/SilkyPix.

They don't look that much better than the paired JPG (for obvious reasons of the extreme lighting) -
then I have to save to JPG which will lose detail due to its harder compression in red and blue -
I am so to speak back to square one.

It doesn't matter if I can see better results in my RAW editor (which I don't, at least, for the as-is versions) - I cannot find an easy way to displaying it with JPG - other than very low compression (larger files) which can be re-compressed by sites - or my rather crude way of grossly over sharpening and saving to higher compression JPG which probably would not face site re-compression.

I will experiment more with RAW and Pentax DCU/SilkyPix as that seems to work better for me -
but I'd appreciate any advice to help mitigate some of these photographic problems when shooting under magenta light using red and blue LEDs.

Thanks.