Lighting

Posted on by
Back to Lighting...

Variable Electronically Diffused LED Panels (5 replies and 3 comments)

JordonP
2 months ago
JordonP 2 months ago

Hi Roger,

I am currently writing my dissertation, assessing the quality of light produced by established diffusion and bounce materials in comparison to LED fixtures compatible with new diffusion solutions, such as those with variable electronically diffused panels.

In order to support my secondary research, I have created a series of questions to gain insight from industry professionals and specialists on the future of lighting and diffusion. If you feel you can answer all or any of the following questions I would appreciate it greatly!

Additionally, If any other professionals feel they can answer these questions, it would also be appreciated.

Thanks!

Q1. What are the advantages and disadvantages of colour tuneable LED lights?

Q2. What are the advantages and disadvantages of diffusion filters/materials?

Q3. What is your opinion on new LED electronically adjusted diffusion panels and what do you know about them?

Q4. Do you think electronically diffused LED panels can replace industry standard diffusion filters/materials and why?

Q5. How popular are electronically diffused LED panels and do you think manufacturers will produce more?

Q6. Where do you see electronically diffused LEDs in the industry currently?

Q7. What is the longevity of electronically diffused LED panels compared to diffusion filters/materials?

Roger Deakins
2 months ago
Roger Deakins 2 months ago

Well, I for one have no idea as I have no experience of 'electronic diffusion'.

The Byre
1 month ago
The Byre 1 month ago

With all this C19 lockdown, I have had time to experiment with lighting, cameras and all things in-between such as lenses.  

LEDs for film definitely get the thumbs-down from me because they alter the quality of the light in some very strange ways.  For example, if you tune one of those RGB lights to 'warm tungsten' you can turn some people's faces red, esp. if they have darker skin.  A cold light setting can turn some Asian skin tones to look green.  

Someone posted a video on YT showing an ordinary yellow pepper under the light of a SkyPannel and under the 'warm' setting it went orange.

LEDs are great for TV work as they use less power and that has great implications for audio work.  TV studios used to be 'fan-city' as all those tungsten lights generated so much heat that had to be extracted.  LEDs mean that most of those noisy fans could be switched off - and that means that one does not always have to close-mic every speaker with a lapel-mic.

RGB LEDs were a great gift to stage work as the need for giant auxiliary generators for touring larger shows diminished.  

The problem for LEDs for film is that our eyes see three broad ranges of light that overlap slightly, allowing us to see all the colours between pure green, red and Blue.  Digital cameras see three specific frequencies - alas, LEDs produce three specific frequencies as well but not always the same ones as the sensor in a camera.  Hence the strange colours one sometimes gets.  The collective wisdom (from those who know more about these things than I do) is to use white LEDs and put colour filters in front of them. 

As for the electronic diffusion - I've seen them in action and they use those crystal sheets that go clear when a DC current is put through them.  A neat trick and probably very useful for TV work where time is everything, or where one has to take all the kit into a building for shooting an interview.

The huge advantage that LEDs have brought me is the fact that all those lovely tungsten lights that otherwise would cost a small fortune, are now being thrown out by bands, lighting companies and theatres and one can pick them up with bulbs for nothing or next-to-nothing!

gabj3
1 month ago

May I ask what LED's you where testing? The reason being is the issues you described are quite common and are being addressed especially in more contemporary (upmarket) LED’s.

(I’d just like to say I am no colour scientist.) The chromaticity (‘colour’ disregarding luminance) of a black body changing temperature doesn’t have a linear path. It follows the ‘Planckian Curve’. A better less scientific way of saying it is that colour temperature or the temperature of white light doesn’t follow a linear path in a chromacity space (gamut etc). This definitely causes some issues. As LED manufacturers for a time believed you could achieve different white light kelvin temperatures by mixing at different intensities a cool white phosphor/node (forgot the term) and a warm white node. This makes logical sense, however as said above it isn’t linear. They where trying to match the path of a curve with an X and Y point. Trying to match a curve with a straight line. This, obviously, didn’t work. It would shift off course, leading to a colour shift! When going to warmer temperatures the linear path would go off course under the curve into magenta!
This can be addressed by adding more phosphors of different colours and it will attempt (in some fixtures successfully) to map the path of the curve, sometimes matching it pretty well, leading to no noticeable (even by the camera) colour shifts.

The other issue is of course then matching it to that of the camera. The quality of light in it’s original context, softness, hardness etc doesn’t change. It can give a more synthetic feel as often fewer colours can be resolved under such narrow frequency bands of light some LED’s emit.

A good way of looking at it is that LED’s are unharmonised to camera technology. They just don’t go together… yet. Already in the last year the technology has improved drastically, discoveries being made etc. The tech is in it’s infancy.

JordonP
1 month ago
JordonP 1 month ago

Thanks The Byre for taking the time to respond!

Would you be able to provide you full name and profession?

JordonP
1 month ago
JordonP 1 month ago

Hi Roger,

Since electronically diffused panels are very new on the market I'm not surprised. I don't think the effect of Covid in the industry has helped with people getting to use the technology offered in fixtures such as Rotolight's Titan X2, which seems particularly geared to professional cinematic lighting.

Perhaps a better question for you then would be are electronically diffused LED's something that you think could be used within the industry, more specifically in High-End TV and Features? Have you heard of anyone using this technology in the past year?

G.C.
1 month ago
G.C. 1 month ago

Hello,

The Rotolight Titan is, to my knowledge, the only fixture that currently has variable diffusion. They’re using an translucent LCD panel in front of the light and you can vary the transparency of the material.

I suspect most DPs/gaffers will almost always use it on the maximum setting… and then add another diffusion in front of it, because on the Titan X2, even at the maximum setting you can still see individual LEDs through, which is a sign that the light is still a bit specular (or “hard”). I think the real benefit isn’t diffusion and making the source softer, because to make a source really softer you need to increase its size (so my answer to your Q4 would be “no” for this reason). I see it more like a spot/flood control on the beam angle on a soft light, which is already a great feature! It is like having a Skypanel intensifier, but accessible in a second by the turn of a knob.

I can see more lighting units having this feature in the future, but for now, the ratio between the benefit to the user and the cost of the tech keeps the feature pretty niche.

MattBendo
1 month ago

This is an interesting take on this G.C! Thank you. I saw the Rotolight at a trade show early last year and I thought this tech was pretty interesting. Looking forward to seeing how it develops.

JordonP
1 month ago

Thank you, for taking the time to respond, G.C

Would you be able to provide your name and profession?

Back to Lighting...