CS194 Project 2: Building a Pinhole Camera
Matthew Waliman, Albert Linh Pham(fa 16), Annalise Hurst(fa 16)

Before lenses were introduced to the process of capturing images, many used pinhole cameras. A pinhole camera is small light-proof box with a pinhole on one side to allow light from a scene to pass through and project an inverted image of the scene onto a screen on the other side. This process is known as the camera obscura effect. The earliest written record of the camera obscura effect dates back to 500 BCE, where Chinese philosopher Mozi correctly stated that because light travels in straight lines from it's source, this causes the image to be inverted when the image's source light passes through a pinhole. Many occurrences of camera obscura effects appear in everyday life, such as holes in the canopy projecting images of the sky on the ground.

In this project, we had to create a home made pinhole camera. Since the pinhole size is so small the amount of light that enters the box at any given moment is very little and makes it hard to see the projected image with the naked eye. To collect enough light to make the image visible, a camera has to be attached to the pinhole camera to take a long exposure image of the projection.

Box Design

We followed the basic design for a pinhole camera and built our camera obscura using a DSLR, a shoebox and some black paper. The entire box was covered to ensure that no extra light was able to enter it and ruin the captured image.

Pinhole Sizes

For our camera obscura we tried three different pinhole sizes. The smallest size was 1mm and it produced the clearest images, however the images tended to be the darkest. The next size larger was 2mm and it produced fairly clear images and had a nice amount of brightness. The largest size was 3mm and the images taken with that size were the brightest but they were also the most blurry, though you could still discern the contents of the image. We decided that the diameter that did the best was the 2mm because though it wasn’t the least blurry the difference between it and the 1mm was very small and it had a better amount of brightness.

fence
1mm
fence
2mm
fence
3mm
hall
1mm
hall
2mm
hall
3mm
tub
1mm
tub
2mm
tub
3mm
hammock
2mm
passion
2mm
cloyne
2mm
court
2mm

Many of the earliest to make use of the camera obscura effect to project images did so in large dark rooms, instead of small boxes, using the same setup as the pinhole camera but on a larger scale. They would make a small hole on one side of a completely dark room which would let a small amount of light int to project an inverted image of what was outside the room onto the opposite wall. To create this effect in a dark bathroom, foil was used to cover the only window and then a hole was poked into it. Since the opposite wall was so far away from the window a sheet was put up to capture the scene. Detailed outlines of the trees and a bit of the roof outside the window could be seen, but there was not much color. A piece of semi-translucent paper was then held up to the hole to capture the scene. This view contained more of the scene and had color.

For comparison, here is a picture taken of the view outside the window next to a rotated and scaled version of the image captured by the sheet of paper.

Light painting is a photographic technique that uses long exposure photographs to capture the movement of light in a single image. Since cameras collect light overtime, having a long exposure allows an image to have the light from a single source appear in different locations. This can give the impression of a painting of light if the light source is moved around while the picture is being taken. While experimenting with light painting the resulting images showed that places where the light was held longer became brighter spots in the image, and that one could give the illusion of separate light sources by covering the light while moving it to a new location and then uncovering it again. This technique was used to create a light smiley face.