The makers of kitschy commercial religious art of the Christian persuasion should be grateful to the telescope builders of the world for so often putting the secondary mirror struts in a cross shape.
It leads to lots of starry photos like this (http://en.wikipedia.org/wiki/Image:Pleiades_large.jpg), thanks to diffraction. Stars don't usually look like that to the naked eye, but the cross-shaped diffraction spikes have, I think, influenced a lot of modern iconography of such things as the Star of Bethlehem.
Hmm, that's a question worth investigating in itself--do depictions of Stars of Bethlehem with cross-shaped spikes coming out of them predate the invention of the telescope? It would be interesting either way.
Here's a nice one with T-shaped spikes (http://en.wikipedia.org/wiki/Image:L_Adoration_des_Mages.jpg) (like a tau cross, I guess) from the 1400s. I hadn't seen that before.
There are a lot of ways to see rays coming out of a star or other bright light. Just squinting will usually create the appearance of vertical rays, and anyone who's seen a lamp through a sheet or a piece of fabric is familiar with cross spikes. And, of course, prefiguring the cross in the Star of Bethlehem is an obvious enough visual trope that I wouldn't be surprised to see it appearing early on.
But I still think the spikes in telescope images have fed back heavily into the modern imagery.
According to wikipedia, which is always suspect, reflecting telescopes were invented in the 16th c. But I suspect various types of aberration in the lens of the human eye could account for as much of this as you wanted to attribute to it.
Coincidentally, yesterday I was just reading about tunable wearable optics (http://www.cvs.rochester.edu/williamslab/r_contacts.html) for correcting higher-order aberrations of the lens. Interesting stuff.
As far as I know, Isaac Newton invented the reflector sometime in the 17th. Most modern reflectors are some descendant or other of the Cassegrain, which was actually invented not much later.
I've wondered why the classical Greeks didn't invent it -- didn't they have the math, and the basic idea that light goes in straight lines and reflects at equal angles? Though that'd still leave you without a lens for the eyepiece.
Ooh, I wish I'd known that back when I was on Ghost Hunters boards. Some really gullible people thought they'd seen some kind of "ghost star" in a photo, where I was sure a bright star (the ghost star! ooh, scary!) had been cut 'n' pasted in. The star that was pasted in must have been photographed by another camera with a different lens, since no other star in the photo had the same kinds of spiky bits emanating from it.
Not necessarily--it could be that the bright light was just the only one in the frame that was bright enough to show visible diffraction spikes, from whatever was causing them (maybe the camera aperture).
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Hmm, that's a question worth investigating in itself--do depictions of Stars of Bethlehem with cross-shaped spikes coming out of them predate the invention of the telescope? It would be interesting either way.
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There are a lot of ways to see rays coming out of a star or other bright light. Just squinting will usually create the appearance of vertical rays, and anyone who's seen a lamp through a sheet or a piece of fabric is familiar with cross spikes. And, of course, prefiguring the cross in the Star of Bethlehem is an obvious enough visual trope that I wouldn't be surprised to see it appearing early on.
But I still think the spikes in telescope images have fed back heavily into the modern imagery.
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Coincidentally, yesterday I was just reading about tunable wearable optics (http://www.cvs.rochester.edu/williamslab/r_contacts.html) for correcting higher-order aberrations of the lens. Interesting stuff.
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And besides, the greeks couldn't even get gravity right. Light things fall slower than heavy things, ptui spit!
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