Camera Obscura
Content
Construction of camera obscura with varying aperture sizes and screen distances Co, Harold and Romero Roland Albert National Institute of Physics, University of the Philippines, Diliman, Quezon City
1. Methodology A camera obscura was constructed (shown in Figure 1) using a cardboard box, aluminum foil and tracing paper. The interior of the cardboard box was painted with black spray paint in order to lessen reflection of light inside the box. ax paper attached to a mo!able cardboard slot was used as the screen where the image would form. "ne end of the box was open for !iewing the screen while the other was co!ered with aluminum foil. This foil was then punctured to create an aperture to allow light to enter the camera obscura. The effects of !arying the si#e of the aperture and the distance of the screen from the aperture, along with adding a magnifying lens to the set$up was obser!ed.
Figure 1. %etup used to obtain the images. An %&' amera was used to obtain images proected on the screen. &ong exposure setting (* seconds and + -%") was used to obtain better images.
. Results and !iscussion The camera obscura produced images that were real and flipped both hori#ontally and !ertically. They are real because they are directly formed where the light from the obects actually con!erge. The flipping is due to the fact that light can be thought of as tra!eling in a straight ray. &ight coming abo!e the aperture will hit the bottom of the screen screen while light rays below the aperture will hit the top of the screen.
Figure . /Flipping0 of image after passing through the hole.
Thus, the following images obtained from the setup demonstrate this.
Figure . The original image (left) and the image !iewed using the camera obscura (right).
The si#e of the aperture was also !aried. %maller apertures had darker but sharper images. This is because there is less light passing through the aperture so there will be less o!erlapping of light rays. -ncreasing the aperture si#e produced brighter but less focused images. This is due to more light rays entering and o!erlapping with each other.
Figure 2. The image obtained with a large aperture (left) compared with the image obtained with a smaller aperture (right). 3ote that the right image is more focused but darker than the left image.
The distance of the screen from the aperture was also !aried. loser distances resulted in a wider !iew of the obect while longer distances resulted in #oomed in !iews. Additionally, closer distances to the aperture also result in brighter images.
Figure *. -mages produced with the screen near the aperture (left) and with the screen farther from the aperture (right). 3ote that the right image does not only gi!e a wider !iew of the obect but it is also brighter.
Attaching a magnifying lens right before the aperture resulted in a clearer and less blurred image. This is due to the fact that the magnifying lens ensures that less of the rays /o!erlap0 to form a blurred image.
Figure 4. -mages produced with (left) and without (right) a magnifying glass. 3ote that the right image is slightly more focused.
1. Methodology A camera obscura was constructed (shown in Figure 1) using a cardboard box, aluminum foil and tracing paper. The interior of the cardboard box was painted with black spray paint in order to lessen reflection of light inside the box. ax paper attached to a mo!able cardboard slot was used as the screen where the image would form. "ne end of the box was open for !iewing the screen while the other was co!ered with aluminum foil. This foil was then punctured to create an aperture to allow light to enter the camera obscura. The effects of !arying the si#e of the aperture and the distance of the screen from the aperture, along with adding a magnifying lens to the set$up was obser!ed.
Figure 1. %etup used to obtain the images. An %&' amera was used to obtain images proected on the screen. &ong exposure setting (* seconds and + -%") was used to obtain better images.
. Results and !iscussion The camera obscura produced images that were real and flipped both hori#ontally and !ertically. They are real because they are directly formed where the light from the obects actually con!erge. The flipping is due to the fact that light can be thought of as tra!eling in a straight ray. &ight coming abo!e the aperture will hit the bottom of the screen screen while light rays below the aperture will hit the top of the screen.
Figure . /Flipping0 of image after passing through the hole.
Thus, the following images obtained from the setup demonstrate this.
Figure . The original image (left) and the image !iewed using the camera obscura (right).
The si#e of the aperture was also !aried. %maller apertures had darker but sharper images. This is because there is less light passing through the aperture so there will be less o!erlapping of light rays. -ncreasing the aperture si#e produced brighter but less focused images. This is due to more light rays entering and o!erlapping with each other.
Figure 2. The image obtained with a large aperture (left) compared with the image obtained with a smaller aperture (right). 3ote that the right image is more focused but darker than the left image.
The distance of the screen from the aperture was also !aried. loser distances resulted in a wider !iew of the obect while longer distances resulted in #oomed in !iews. Additionally, closer distances to the aperture also result in brighter images.
Figure *. -mages produced with the screen near the aperture (left) and with the screen farther from the aperture (right). 3ote that the right image does not only gi!e a wider !iew of the obect but it is also brighter.
Attaching a magnifying lens right before the aperture resulted in a clearer and less blurred image. This is due to the fact that the magnifying lens ensures that less of the rays /o!erlap0 to form a blurred image.
Figure 4. -mages produced with (left) and without (right) a magnifying glass. 3ote that the right image is slightly more focused.
