Home Entertainment – Bias Lighting

Not content with being a computer geek, I’m also a bit of an audio/visual geek. Which is right where this post fits in.

My current set up is a 50″ LG 3D Plasma tv, hooked up to a Yamaha amp and I’m very happy with it. However recently I’ve been reading up a bit on “bias lighting”, I’ll give a bit of a quick summary in this post but I’d really recommend anyone interested check out this excellent blog about it: http://biaslighting.blogspot.com/

In a nutshell, watching TV in the dark isn’t a good idea, nor is it a good idea to watch it with all the lights on. The lights kill immersion and heighten reflections, as well as dim colours. Watching in pitch black can destroy your eyes, with them having to constantly re-adjust to the changing brightness, blacks (as in how dark black looks on the set) can appear lighter too.

So what is bias lighting? In a nutshell it’s shoving a light behind your tv and bouncing the glow off the wall to illuminate the general area of the screen from behind. There’s a bit more to it than that but that’s the general principle. What are the benefits? Well, I’ll just quote them straight off the blog mentioned above:

• Subtle ambient light in the room.
• No lightsource shining/reflecting on the display.
• No need to crank the contrast up.
• Deeper black, helps dark scenes.
• Better colour definition compared to household lighting

In general it’s a cheap way to improve the perceived picture quality of your image, as well as saving your eyeballs.

I figured I didn’t have anything to lose so I set out to see what I could do. I ordered the fluorescent tube linked in the biaslighting blog and after it arrived set about hunting for a suitable fitting. Eventually I found one from Wickes for £9.99. Unfortunately the ballast inside (the thing that powers the light) is magnetic and not electrical. Magnetic ballasts operate at roughly 50hz which can have a visible flicker, Electrical Ballasts operate at a much higher frequency meaning the flicker isn’t visible.

After some DIY I replaced the big ‘ole magnetic ballast with an electrical one I ordered from ebay. Thankfully I didn’t blow the house up and the operation was a complete success.

Armed with picture wire and duct tape I went about the task of attaching it to the tv.

As you can see above I’ve attached the fitting to the tv using plenty of duct tape, it doesn’t look too pretty but it’s solidly attached. I’m not bothered about the aesthetic value as no-one will ever see behind there (well, other than anyone reading this). Next up I switched it on and checked out the glow, it looked pretty good but I felt too much light was lost out of the top, so I cut off some of the cardboard from the packaging, wrapped it in duct tape and fastened it on to the top to control the light.

Success! The tv now has a pleasant glow coming from the back of it. The light has a colour temperature of 6500k, which is as close to ‘natural light’ as I’m likely to get. The benefit of this is (again, copying from the biaslighting blog):

"The common incandescent lighting that you have in your home is generally tuned towards the ‘yellow/orange’ side of the spectrum. However, everything you watch from games to movies and broadcast TV was colour-graded in an environment tuned for 6500 Kelvin. In simple terms, this is ‘midday sun on a clear day’, so more tuned to the cool blue side of the spectrum.
When you watch the TV with ambient conditions that deviate away from 6500k, your whole perception of colour gets altered.

As an example, say your display was showing a 100% white frame. The light in the room will affect how blue, green or red that white colour will appear to shift towards. If your display is already a little too blue or green or red in the first place, then the room lighting will only exaggerate that further.
Most of us have walls that are coloured to some degree, or curtains and furnishing that shift our perspective of the colours we see onscreen. Sometimes subtly, sometimes dramatically. For the most part, that can’t be helped, we don’t all live in a grey submarine where everything is perfectly neutral and drab. But getting a suitable bias light as close to 6500k as possible, will get you significantly closer to reference standards than relying on typical household lighting."

So in layman’s terms, having the right colour light makes the picture look as it should.

I’m going to dim it down a little and block out the light from the bottom (it highlights my messy wiring!). All in all though it makes night watching much more pleasant, as Scott Pilgrim here demonstrates.

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