Camera Obscura

Computational Photography: Project 4 (Grad)

Matt Mukerjee and Ashique Khudabukhsh

(mukerjee at cs, akhudabu at cs)


Overview:

In this project we seek to create a physical artifact, the camera obscura, by making a shoe box lightproof and capturing images projected on the backplane of the shoe box. Although traditional camera obscura, or "pin-hole cameras," rely on photo-receptive film as a means of capturing the images, our work uses a digital camera to actually capture an image of an image, making it a post-modern, meta-camera. In order to test the effects of various aperture (or "pin-hole") sizes, we puncture three separate stacks of index cards, creating three distinct apertures with diameters roughly 0.1 mm, 1.0 mm, and 5.0 mm. We then seek to analyze the quality of images of the same scene captured with the different aperture sizes.




Results:




Our (post-modern, meta-)camera




HUGE (~10mm)

BIG (~5mm)

MEDIUM (~1mm)

SMALL (~0.1mm)

Outside

Inside

Various


Green Soda Bottle


Telephone Receiver


Guitar Headstock


Flashlight w/tripod


Dis
scussion:
Being first-year grad students, we know little of this "sunlight" that we hear undergraduates whisper about in the hallways.



Thus we had some trouble getting our camera obscura to work, due to lack of light. The day we got a chance to try it out outside was a miserable cloudy day. Thus, in the top row of images, we can only see the building we were looking at (Purnell, next to the CS buildings), when the aperture is opened very wide. Eventually, with smaller apertures, too little light is let in, producing a very dark image. Surprisingly enough, taking pictures indoors actually worked well. As you can see, the images themselves get sharper, but darker as the aperture is made smaller. Additionally, please note that the images are inverted in both the x- and y-axes, as is traditionally present in camera obscura. Furthermore, the cheap point-and-shoot camera we used (which was the best we could find for the assignment), had a maximum exposure time of ~8 seconds, which contributed to the dark images we captured. At the bottom of the table, we see various objects captured by our camera obscura using the HUGE aperture. These were all done indoors, like the second row of images. Interestingly enough, our green soda bottle actually appears to be green in the image. Pretty classy.

Bells and Whistles:

BW 1 (Shadow Puppets):

BIG (~5MM)

MEDIUM (~1MM)

SMALL (~0.1MM)


Discussion:

In our attempts to verify the correctness of our camera obscura indoors, we used a bright point light source and our hands to capture images of shadow puppets on the interior screen. Again, they get harder to see as the aperture size is reduced.