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camera obscura Answered

i've been trying to figure out how to make a camera obscura. i have seen a diagram of one but i can't find any instruction on how to make one. the cheapest one i've seen for sale is $198. i want one so i can use it to draw, so preferably a small camera obscura as opposed to room sized. does any one know how to make one or where i can get more information on doing so? thank you!!

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craftyv (author)2010-10-17

Please have a look at a book by David Hockney the UK artist who has written a book about this and shows a variety of camera obscura. The book is about art and how even "ancient" artists used them. Sorry can't remember the name of the book but it's well worth a look. Good looking.

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jasmine_nora (author)2007-05-24

okay. thanks for the help. the one that i was trying to make was using a mirror so the image would project straight up, and i could trace from the top of the box. i didn't use a lense though, and that may be where i went wrong.

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LasVegas (author)jasmine_nora2007-05-24

Yes. A mirror would work fine for projecting to the box's top, but at least one lens is absolutely required. Any old magnifying glass would do.

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jasmine_nora (author)LasVegas2007-06-05

okay, so i'm having some difficulty with the camera obscura. i placed a mirror inside so the image would project upward (and i bought a magnifying glass). is the image supposed to actually project onto the plexiglass , or are you just using the plexiglass top to have a hard surface to trace onto? and the image that you see is actually just the image that is on the mirror? because the image that i see is just a small round image (about the size of a tennis ball on my paper) that is projected onto the mirror. does this sound right? sorry this is so confusing...but i'm confused!! thanks!

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LasVegas (author)jasmine_nora2007-06-05

You're right... The Plexiglas is just to create a hard surface to draw on. With a single lens. your only going to get what's within the lens. The further your trace paper is from the lens, the larger (and dimmer) the image will be. Perhaps your box is too small. It sounds like you're having some success! I'd like to see pictures of your work!

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jtobako (author)LasVegas2007-06-06

Focal length may end up being a problem. I believe that the original camera obscura were pin-hole style, and didn't need a lens but did need a dark room.

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Weissensteinburg (author)jtobako2007-06-06

Actually, the first camera obscura used a far sighted man's glasses as a lens.

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jtobako (author)Weissensteinburg2007-06-07

Camera_obscura

Turn of the (first) millennium camera obscura was a pin hole.

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Weissensteinburg (author)jtobako2007-06-07

All cameras have lenses, even pin holes. With a large room, just a small hole wouldn't work. They used far sighted glasses. Trust me, this was drilled into use in photo class.

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I've used pinhole cameras many times, and the principle is the same as a camera obscura. A camera obscura usually uses a bigger hole and a bigger room. What differentiates it from a normal camera is the fact that it doesn't use a lens.

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Pinhole cameras are camera obscuras, not all camera obscuras are pin hole cameras. The smaller the hole, the more focused your picture will be. Making a larger hole would ruin your image. For that reason, large camera obscuras can have a lens, allowing more light while remaining focused. If you like wikipedia, "Some practical camera obscuras use a lens rather than a pinhole because it allows a larger aperture, giving a usable brightness while maintaining focus." http://en.wikipedia.org/wiki/Camera_obscura

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I built some drive electrics for Camera Obscurae built by an old friend, we had a very nice flat mirror which could be tilted and spun, which brought light into a very very expensive triplet lens, working at about F10. The resulting field was flat on a 5' diameter table. The triplet cost 5000 USD.

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jtobako (author)Weissensteinburg2007-06-07

The pin hole ACTS like a lens, giving an image that is in focus at any distance at the expense of the amount of light available due to it's tiny appature.

Start with wikipedia and continue with google

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jasmine_nora (author)jtobako2007-06-06

so are you suggesting a longer box? longer cylinder? the one i have is about 11x11 and the cylinder (attached to magnifying glass) is about 5 inches long. is there a way to get the image square, rather than round like the magnifying glass? i have seen some camera obscuras, and it shows the image as square/filling up the plexiglass area.
here's an example:
http://cgi.ebay.com/Solid-Mahogany-Replica-of-18-19th-Cent-CAMERA-OBSCURA_W0QQitemZ290126361591QQihZ019QQcategoryZ4701QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

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jtobako (author)jasmine_nora2007-06-07

I'm curious about how many millions of candlepower had to be used to get that picture : ) My own experiments haven't been anywhere near that bright. The focal length of the lens and the distance to the target determine how long the box has to be-that's why the length is adjustable. Making the image square is done by masking off/not looking at the whole image. The use of a cylinder may be blocking/masking the light from the lens, making the image small.

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jtobako (author)jtobako2007-06-07

Just found some plans. pdf and the original link to the plans here.

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jasmine_nora (author)2007-05-24

awesome, i'll try it and let ya know how it goes. thanks!

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LasVegas (author)2007-05-23

It's actually quite simple. I used to make them when I was a kid. 1) Find a lens 2) Tape it to the end of a short tube (2-3") about the same diameter. 3) Cut a hole into a box the same diameter as the tube and fit the tube into the box. 4) Tape a white sheet of paper on the opposite side of the box to cover the entire opening. 5) Aim the lens at a bright source (like the TV or out a window) and adjust the tube to focus. The picture will be inverted on the paper.

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The only amendment I'd offer is to use tracing paper.

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Yes. replacing the paper with clear Plexiglas would allow the use of tracing paper to transfer the image.

As I kid, I was happy with just the image. Kinda cool watching George Reeves upside down. :)

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Weissensteinburg (author)2007-05-23

If you want it for drawing, just get an overhead, or an elmo projector.

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