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| Room Camera Obscura: |
Introduction:
Camera obscura is derived from latin to mean darkened room. The earliest mention of a device similar to a camera obscura was made by the Chinese philosopher Mo-Ti (5th Century BC). He inverted an image into a darkened room through a pinhole. Aristotle was said to understand the optical illusion of the camera obscura as he viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes of a sieve and the gaps between leaves of a plane tree. In 1490, Leonardo Da Vinci gave descriptions of camera obscuras in his notebooks.
The first camera obscuras were darkened rooms, like Dutch Scientist Reinerus Gemma-Frisius used to view a solar eclipse in 1544.
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| Lucida in use:http://en.wikipedia.org/wiki/File:Cameralucida01.jpg |
The images were improved with the addition of a convex lens on the aperture in the 16th century. The later addition of a mirror to reflect the image onto a viewing surface. A camera lucida is the term used when the image is reflected down onto a viewing surface. Giovanni Battista Della Porta suggested in his book Magiae Naturalis published in 1558, that these be used for drawing assistance.
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| room camera obscura illustration |
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| Riva Degli Schiavoin, Venice, Canaletto, 1740 Painted with the use of a camera obscura. Grand Tour Gentlemen would purchase these type paintings because it looked like how it looked when they saw them, alive and with the right perspective. |
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| Johannes Kepler Tent obscrua: |
The term "camera obscura" was first used by German astronomer Johannes Kepler in the early 17th century. He used a portable camera for surveying in Upper Austria. In the 17th and 18th centuries, artists used portable camera obscuras to assist in their drawing or realistic scenes. Such artists include Jan Vermeer, Canaletto, Guardi, and Paul Sandby. By the beginning of the 19th century, the camera obscura could be used with photosensitive paper with little to no alteration in design.
Room camera obsuras were popular in the 19th century as well, used as for education and entertainment. With the addition of a lens, the images could become bigger and crisper. They were placed in parks with beautiful scenery, along beaches, and other places of interest.  |
| Postcard: Famous Camera Obscura Santa Monica, Calif. c.1900 http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html |
Some camera obscuras can be seen here: http://brightbytes.com/cosite/portable.html
Some camera obscuras found in US parks can be seen here: http://brightbytes.com/cosite/portable.html
This information was summarized from: http://brightbytes.com/cosite/what.html
Additional Links –
Timeline of the History of Photography: http://www.historiccamera.com/history1/photo_history300.html
[click two page advances to find information on camera obsucra]
Timeline of Historic Cameras:
http://www.historiccamera.com/historiccameras/historiccameras.html
Video:
What is a camera obscura and how does it work: http://www.youtube.com/watch?v=tmAPtrpdoZw
Book: http://books.google.com/books?id=00gWAAAAYAAJ&printsec=frontcover&dq=Camera+obscura&hl=en&ei=EfarTdShNITl0gGjlYH6CA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDQQ6AEwAg#v=onepage&q&f=false
Process:
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| camera obscura with mirror: |
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| http://wikis.lib.ncsu.edu/index.php/GD_342/Glossary |
Traditionally, the boxes were made of wood and a piece of grounded glass would be placed wherever the screen is required. The grounded glass captures the image. Sliding camera obscuras can be used, and this is where the lens can move farther away from the screen in order to focus, like zooming on current cameras.
A camera obscura can be made out of anything. From paint cans to tins, Pringles cans, cardboard boxes (ex. Cereal boxes, Pop Tart boxes, etc), anything can be used. The goal is merely to provide a dark space in which to view a screen on which an image is projected from through a lens or pin hole. Pin holes will provide an image, but when using a lens, the image will be clearer. Plans for camera obscuras can be adjusted in whatever fashion in order to achieve this goal.
How they work:
When light hits an object, it reflects the image, like a seeing your reflection on the surface of a pond. When the light rays, when narrowed by a hole or a lens, will focus the light and rays flip, thus flipping the image. A lens will focus the image more than a pinhole by bending the light. The screen or back of a room, catches the image, upside down. If the image moves closer or farther away from the hole, the image within the camera obscura will adjust and grow fuzzy as it cannot focus. These pictures help demonstrate how light travels and creates the image.
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| Example of light bending with contact of a lens, the grass being a lens, then the direction/trajectory of the shopping cart being the light. When the rays of light contact the lens, they bend and alter which can lead to distortions in the actual image, a fishbowl effect. |
http://en.wikipedia.org/wiki/Lens_(optics): a good site for a quick review of how lenses work with plenty of pictures showing light traveling through various types of lenses.
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| http://rctc-photo-1.blogspot.com/2011/01/web-work-2.html |
My Camera Obscura Project:
For my camera obscura we used a lens to focus the image. When using a lens it is necessary to measure the focal point of the lens. I used a magnifying glass I bought at a hardware store for a few dollars, even though we were given a plastic magnifying glass for class. I decided to use my own image as it was clearer. The plastic magnifying glass we were given did not have a smooth surface and thus distorted the image. The glass magnifying glass was clearer, however, it will alter the focal length, making it different from others in class that used the given magnifying glass.
To measure the focal length, the glass was held up near a wall with a window behind it. The image of the window will appear on the wall. Moving the lens forward or back from the wall until the image is clear is the proper focal length. I then measured the distance of the lens from the wall to discover the focal length. The focal length was quite small, about 65mm. Others in class had focal lengths of up to six inches.
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| lens taped in toilet paper roll |
The next step I did was to make a tube to hold the lens. Cutting the toilet paper roll down one side, lengthwise from opening to opening, I adjusted to opening to around the lens and then taped it around lens. It is important to know how far the tube open is behind the lens as it plays into the focal length. The tube was too long and I cut it down to shorten it. I then put the tube against the box that would be the camera obscura, and traced the circle to cut out. Once cut out, the circle allowed the tube to be inserted into the box. Tape around the end of the tube ensured a nice fit.
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| Disassembled Camera obscura. Lens detached from box. Box opened to show screen inside and hole for viewing. |
Coffee filter was too dark. An image could be seen but it wasn't very clear. It was hard to tell if the focal length needed adjustment or if the screen needed to be thinner, clearer.
The greyed plastic binder was too clear. The circle of light was too bright and bleached out most of the image in the center of the screen. However, on the outskirts of the image, I could make out a faint, ghostly translucent image. This was too clear. I attempted three sheets of plastic to increase the density, but the image remained too clear for each. I decided to try finding something to place between two sheets of plastic and decided on two ply tissue, but separating the ply to make just one.
With the tissue in between, the image could be seen, but it still wasn't as clear as I would later see with wax paper. However, after adjusting the screen and the tube a little for maximum clarity, it made a clear image. Once wax paper was made available, I replaced the tissue and the plastic with wax paper. The image was clearest in this method. After finding the clearest screen, I adjusted the tube, pushing it in and out to see if the image could become clearer. I managed to make a very clear image.
The short focal length made it necessary for the camera obscura to be very close to the image you actually wanted to see, about two feet or so from the front of the tube. The image is upside down, because of the way the light comes in through the lens and then flips as the rays of light that hold the image cross and project an upside down image on the screen. A mirror could have been used to project the upside down image onto the top of the camera obscura, where the screen would then be placed. This would right the image orientation. However, I decided not to use a mirror, though I thought it interesting to try.
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| Upper right corner shows image through camera obsura (flipped for clarity, would be upside down) Distance required for clear image shown in left picture. |
My courses link I found helpful in this project (probably only accessible by RIT students enrolled in the class): https://mycourses.rit.edu/d2l/lms/content/viewer/main_frame.d2l?ou=334489&tId=1750709
Additional Information:
A great link that tells a lot on camera obsuras and more: http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html
Whole rooms can be turned into camera obscuras, such as your bedroom. By applying the proper lens or hole in a shade that blackens the room, in the morning when the sun comes up and light shines on the outside, the image of outside will be inverted into the room for as long as it remains dark. Opening the shade will obviously make it too bright to show the image that would be projected on the wall.
To do this yourself with more specifics follow this link: http://www.funsci.com/fun3_en/sky/sky.htm
BBC: A camera obscura room: http://www.youtube.com/watch?v=RuJ_Jd6Qgyo Great Video! We should totally do this in a classroom J
Summary:
Camera obscuras and lucidas alter light into images by concentrating them onto a surface. Making camera obscuras in parks must have been truly entertaining in the day - to spy on someone and not being seen. To make a large room size camera obscura seems like the greatest experiment. It would seem that a portable camera obscura works best with a wax paper screen. It would have been nice to be able to see things farther away within the camera obscura but the lens picked did not allow for that. If this project was to be redone, it would be best to evaluate several lenses to pick the right one for a clearer, farther picture.
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| 19th Century Cartoon depicting Camera Obscura http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html |
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