The B3TA Detective AgencyUniversalpsykopath tugs our coat and says: Tell us about your feats of deduction and the little mysteries you've solved. Alternatively, tell us about the simple, everyday things that mystified you for far too long.
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Scaryduck LIKES EGG, Thu 13 Oct 2011, 12:52)
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Psychedelic ScienceI remember as a wee nipper seeing an exhibit in the Science Museum. It consisted of a white tiled piece of wall with black raised lines that resembled the stained glass window of a church, showing the Madonna and child, but completely colourless.
There was then a small round window in front of it that you could look through, and you'd see the image in startling, brilliant colour. There was also a knob below it that you could turn, and make the colours change.
This had stuck in my head for years as some sort of magic window into another dimension. And it was only decades later that I figured out how it was done. And I'd love to see it done again.
You project two bright colour images, one the exact colour inversion of the other, onto the same screen so that when combined, they appear white. The thick black lines, already on the screen, mask any fringing at the edges. One projector has vertical, the other horizontal, polarisation. You then look at it through a polarising filter, which you can rotate to alternate the colours.
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joefish It's hard for thee to kick against the pricks, Thu 13 Oct 2011, 19:51,
3 replies)
Cheers for that!I remember also seeing that as a child and wondering how it was done, but never figured it out and eventually forgot about it.
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benryves Now I'm radioactive! That can't be good!, Thu 13 Oct 2011, 21:58,
closed)
it was also how they "healed" the lepers in the 1920s film about Jesus...Red and Blue being indistinguishable on a B&W camera, they made the "spots" on the lepers blue, then had a filter that was half-red and half-blue. Rotate from red-to-blue and the spots disappear as far as the camera is concerned. They did the same in reverse to do a Jekyll-to-Hyde transformation in front of the camera, too - clever stuff and the guy who did the effects kept it a secret until the day he died, just to keep the magic alive. Isn't physics great?
(, Mon 17 Oct 2011, 15:25, closed)
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