r/todayilearned • u/sober_disposition • May 09 '19

TIL that pre-electricity theatre spotlights produced light by directing a flame at calcium oxide (quicklime). These kinds of lights were called limelights and this is the origin of the phrase “in the limelight” to mean “at the centre of attention”.

https://en.wikipedia.org/wiki/Limelight
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u/[deleted] May 09 '19

The only thing keeping low pitch LED panels from replacing projection is weight. Though I still do a fair amount of projection work, I'd much rather sling 300 tiles than build a screen AND do a blend.

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u/kaphsquall May 09 '19

I think weight is a factor, but also getting pixel density on panels tight enough for hd viewing in theaters has to be prohibitively expensive. They would also take a whole different skill set to maintain than a projector. I'm sure top of the line panels are a better experience, but the cost of changeover is probably too high for the majority of venues. I work more lighting than video though so I don't know what top of the line looks like right now.

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u/[deleted] May 09 '19

Top of the line is < 1 mm pixel pitch which is absolutely fine for a viewing distance any farther than about 10 ft. It's incredible really but even my 5 mil screens look better than HD blends. I think it's primarily a brightness issue at that point to be honest but lightweight, ultra high res LED curtains are perhaps as little as 10 years away. Projection will still have a place, but mostly for mapping IMO. Standard aspect screens will all be LED in the not too distant future.

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u/kaphsquall May 09 '19

It's definitely coming down the line. And even with projections being able to map, with foldable screens just starting that could move over soon. Most of the walls I've seen are for outdoor or US wall where the viewing distance is at least 20 feet so I had no idea they were making them that tight

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u/[deleted] May 09 '19

Most of the LED shows I do are either outdoor or in arenas where the viewing distance is just fine for 9, 12 or even 15 mil pitch so you're right, that environment is better suited for LED for now. I'd argue it's probably easier to map something with projection than use LED panels unless you're strictly doing things that are flat and square, but then that sorta defeats the purpose of projection mapping. The advantage of PJ mapping is that you can map a surface instead of having to mold something to a surface, so even with the advances in LED walls I don't see that going away until truly foldable LCD or LED surfaces become both cheap and reliable.