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   Jake Rodkin (ja2ke@idlethumbs.social)'s status on Monday, 08-Apr-2024 03:33:54 JST Jake Rodkin

   This video from Corridor Crew is pretty amazing. They re-create the nearly perfect compositing from the penguin dance sequence in Mary Poppins, which was achieved using high intensity sodium vapor lights and a very custom beam splitter, instead of a blue or green screen. It truly feels like a lost art rediscovered. When the matted footage just perfectly drops in I gasped haha https://m.youtube.com/watch?v=UQuIVsNzqDk

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     Mrs Beanbag (mrsbeanbag@ieji.de)'s status on Thursday, 02-May-2024 20:01:56 JST Mrs Beanbag

     in reply to

     • Robert J. Berger
     • jaseg

     @ja2ke @jaseg @rberger came here to say basically the same thing about LEDs so i looked it up, i always thought LED light was essentially monochromatic unless you purposely widened it, but of course nothing's perfect is it.. bandwidth of 29nm might still be usable though? or you could put a filter on the light as well.

     now here's another idea though: tetrachromatic CCD. so you don't even need two cameras

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     Jake Rodkin (ja2ke@idlethumbs.social)'s status on Thursday, 02-May-2024 20:01:57 JST Jake Rodkin

     in reply to

     • Robert J. Berger
     • jaseg

     @jaseg @rberger thanks for this thread it was an interesting read! (I almost said illuminating but then caught myself)

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     jaseg (jaseg@chaos.social)'s status on Thursday, 02-May-2024 20:01:58 JST jaseg

     in reply to

     • Robert J. Berger

     @rberger @ja2ke btw, if you want a "single frequency LEDs" with much narrower bandwidth, a diode laser is essentially that. You pay with both cost and efficiency though. Also, a laser puts out light that is both narrowband and coherent, and if you don't care about the coherence, it can be a nuisance since it causes speckles from interference when you illuminate an area with laser light.

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     jaseg (jaseg@chaos.social)'s status on Thursday, 02-May-2024 20:01:59 JST jaseg

     in reply to

     • Robert J. Berger

     @rberger @ja2ke LEDs have a substantially larger bandwidth than a sodium vapor lamp, but if they are too broadband depends on how narrowband their filters in the video are. You're right in that you definitely want a straight yellow/red/whatever LED instead of a phosphor-converted one, as the PC ones have much broader bandwidth, and usually have a peak of the original blue or purple showing through as well.

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     jaseg (jaseg@chaos.social)'s status on Thursday, 02-May-2024 20:02:00 JST jaseg

     in reply to

     • Robert J. Berger

     @rberger @ja2ke That might work. The reason you want a narrow spectral peak in the first place is that you want the background to be about the same brightness as the foreground so it doesn't swamp out the color image, but you want to concentrate as much of that yellow light energy as possible inside of the matte image filter's passband while keeping that filter as narrow as possible because making the filter wider will mess up the color image.

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     Robert J. Berger (rberger@hachyderm.io)'s status on Thursday, 02-May-2024 20:02:01 JST Robert J. Berger

     in reply to

     @ja2ke That was fascinating. I had no idea about the Mary Poppins technique. I wonder if you can make single frequency LEDs instead of Sodium lamps? Seems like that should be easy. I thought that they effectively are and they use phosphors or quantum dots to make them broader spectrum.

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     Anthony Horton (spacelizard@aus.social)'s status on Thursday, 02-May-2024 20:02:06 JST Anthony Horton

     in reply to

     @ja2ke Fascinating! I work in astronomical research and can say that astronomers regularly get beam splitters of exactly this type (separating Sodium light at 589 nm from everything else) custom made for use in our instruments. Our use case is obviously completely different (laser guide stars for adaptive optics) but it's the same optics.

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     jaseg (jaseg@chaos.social)'s status on Thursday, 02-May-2024 20:02:11 JST jaseg

     in reply to

     • gunstick
     • Robert J. Berger

     @gunstick @rberger @ja2ke Yes, there are some techniques. Most of them involve mechanically moving or vibrating some optical component such as a diffuser. To me, they seem too complex compared to buying a couple low-pressure sodium bulbs.

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     gunstick (gunstick@mastodon.opencloud.lu)'s status on Thursday, 02-May-2024 20:02:12 JST gunstick

     in reply to

     • Robert J. Berger
     • jaseg

     @jaseg @rberger @ja2ke can you "decohere" laser light?

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