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Does it have something to do with dentistry?



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Is it something to do with sunlight being focussed by the lens onto the black plastic, then the arc shapes are caused as the sun moves across the sky and the focal point changes?

Can't think of much in America that we don't also get in the UK these days apart from bright sunlight

DING. We have a winner.

Fascinating, huh?
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Tony Fabris