August 19, 2005

How to project an image of the outside world onto a wall in your room "If you put a magnifying glass a few inches from a wall that is opposite a window, you will see the outside view projected upside down on the wall. But if you put a lens on the window and cover the rest of the window with opaque material, the lens will project the outside view over the entire opposite wall, of course you must have the proper size lens for the room."

Via Optical Illusions etc

  • What a cool idea! Have you tried this?
  • This will be perfect for my new place. I've chosen to set up my 'office' in a small room in the basement. There is a window at about eye level, but it's too small to properly illuminate the space. This will make it seem much less claustrophobic.
  • Sounds like an interesting way to brighten a cellar. Or the interior of your treehouse.
  • I do this with my eyes all the time.
  • We all do, supposedly, but our brains insist on turning the seen image 180 degrees around. Never really understood that part.
  • I know. That was why I said what I said when I said that thing I just said.
  • Yeah. Does that mean that the world is actually upside down? IBLEWYOURMIND
  • A bit more about (and examples of) the camera obscura effect. Good post!
  • > our brains insist on turning the seen image 180 degrees around i find i can copy images more accurately if i place them upside down above the page i'm drawing on. > Sounds like an interesting way to brighten ... the interior of your treehouse. do you have a treehouse? wow. i'm very jealous.
  • Used to when I was a boy. But alas! no more, roryk Interesting ye can copy images better that way. I use a mirror when I draw as it allows me to spot areas I need to redo at a glance. Somehow seems to reframe things ....reframes my perception...or something...
  • Shit! beeswacky is a male. Well that's screwed up my navigational equipment!
  • Ahem. Beeswacky is more than just "a male". He is a fine gentleman. *wonders if she can get her deposit back if she drills a hole in her rented room*
  • Alnedra, I'd already deduced that beeswacky was a 'fine person'. But you know how we build up pictures in our head..
  • Yes - peacay looks like a pelican to me, for some reason...
  • Alnedra, I'd already deduced that beeswacky was a 'fine person'. But you know how we build up pictures in our head.. Upside down pictures.
  • Sorry, I didn't mean for it to sound that annoyed, peacay (^_^) yeah, I have the strangest images of people on this site. Kitfisto, for one, will always look like this to me, despite the fact that I've met him before.
  • actually, you don't even need a lens...or even that small a pinhole...depends on the conditions, i guess....was working on a movie in a hotel room once and we were all like "whats that weird shadow on the wall?" and i looked at it and realized it was the palm trees about 1/2 mile away on the horizon being lensed by a hole in the curtains about 6" square...oh, and also...saw an AWESOME pinhole camera photo at the whitney in NYC a few years back it was of an abandoned ww2 shipyard and they used a battleship as the camera...the photo was about 15 feet high by about 50 wide...incredible!....love pinhole work.... oh and also...they now believe vermeer used this technique in his paintings...they know he went to school with von leewenhouk (lensmaker/inventor of the microscope)...so they think thats where he got the lenses....search 'vermeer' on metafilter (think thats where i saw the article...)
  • I'd washed my hair when we met, 'nedra...
  • This is a plot device (or just a device) used in Addicted To Love.
  • OK, here's a somehwat similar question, the other day flipping around on TV I saw something where this guy was talking about the first mirrors were polished brass (or bronse, I can't remember) and they had designes engraved on the back. When the mirror was help up to the light so the sun reflected on the wall, in the spot on the wall you could see the design on the other side of the mirror. Anyone know anything about this??? I tried to google it but couldn't really find anything. I think the show was one of them supernatural shows, so I'm not sure if it was a trick or if this was something that actually works.
  • Yeah, when I was in college, I had aluminum foil over my windows to keep my room cool and dark. I would wake up with a vivid projection of the backyard on the wall opposite the window. The myriad tiny holes that were inherent in the foil made it happen. Just like a camera obscura.
  • "What a cool idea! Have you tried this?" Not personally, and it would be hard to implement where I live now (big picture windows) but I find the idea fascinating. Thanks for the link peacay!
  • Presumably, if people are making this work with ground-level basement windows, we're talking about altering the angle of view, yes? Or else we'd be looking at lawn and sidewalk. If so, it would be great to project the sky onto a wall. A nice afternoon of alto-cumulus would be dreamy.
  • bees > Interesting ye can copy images better that way. i've thought about it and tried copying both ways since. i think the difference is that i get a better feel of the whole picture when i turn it upside down. so this way i'm less likely to misallocate space to some part, i think. i'm also less likely to put my own preferences onto something - an eyelash, say, where i'll always go elliptical but others might go straight.
  • Thinking either upside down or mirror image would give you a fresh way to look at an image so your previous expectation of what you were seeing could be set aside. Dunno otherwise why this works, though it does. In the old days the advice often was to lay down a gridwork of horizontal and parallel lines on the image to be copied, so the whole was then broken into smaller squares. The idea was ye could work on a squared-off section at a time as if each one were were a small, complete picture. This was a technique I found annoying to use since it meant not onlyu did ye mess up the original image, yu also ended up having to do twenty-five or thirty smaller pictures instead of one big one. This seemed to me entirely the wrong way to go about things. Anyway, I never used this technique.
  • Maybe have a look at this.
  • > lay down a gridwork of horizontal and parallel lines on the image to be copied this is a useful way to reproduce drawings on a smaller scale than the original. you set the second grid up as a percentage of the first, so for example the first has squares of 3 cm and the reproduction has squares of 1 cm. i agree that it's tedious as a method, though.