The goal of this project is to design a good pinhole camera and to capture images using it.
When designing the pinhole camera, I had three goals in mind. First, the projected image should be in focus. Second, I wanted to be able to swap pinhole sizes easily and modularly. And third, I wanted to be able to mount my smartphone and use its digital camera for recording the project image.
Keeping the first goal in mind, I used the following formula in constructing the camera:
$$d=1.9\sqrt{f\lambda}$$
Where $d$ is the pinhole diameter, $f$ is the focal length (distance from hole to screen), and $\lambda$ is the wavelength of light. The formula describes the optimal parameters for obtaining crisp pinhole images.
I wanted to be able to create consistently sized pinholes, so I used standard mechanical pencil leads as pins. I had 0.3mm, 0.5mm, and 0.7mm pencil lead on hand. So I chose $d=$0.5mm as my optimal pinhole size. It is advised to capture yellow-green light, at $\lambda=$550nm. With the other two parameters in place, I solved for the optimal focal length and got $f\approx $12.6cm. So, I found a cardboard box with a depth of about 13cm depth and padded the backpane with some tape. I then lined the back side with white printer paper to make the screen, and lined the side panels with black construction paper to prevent extraneous light from reflecting on to the screen. I chose a matte, heavy, and thick construction paper to absorb as much unwanted light as possible. |
|
After lining the insides of the box, I lined two cardboard panels with black paper. With the black side pointing inward, I taped the two panels on to the front of the box to create a slit. |
|
Now with the third goal in mind, I designed a mount for my smartphone camera. There is a small hole for the camera and the rest of the mount obscures part of the slit. My phone fits snugly into the mount, so no unwanted light gets through into the box and pictures can be consistently taken. The mount also features the ability to see the phone screen to configure the camera, and preview images taken. |
|
With the second goal in mind, I designed a similar "mount" for the pinholes. The middle of the box features a pocket with a square hole cut out. The slide cards with the pinholes can easily be inserted into the pocket and swapped out. This means I don't have to tape or retape components of the box every time I need to change pinholes or configure the camera.
|
For taking all of the following images, I used my smartphone's digital camera, which features a Sony IMX298 sensor. Most notably, the sensor allows has "an electronic shutter with variable integration time." This allows for real exposure timings, rather than simulating exposure timing through averaging.
When taking the images, I used manual settings to adjust ISO, exposure time, and focus. For the comparison photos, I used: ISO 1600, 20/15/15 second exposures respectively, and focus adjusted to about 12cm away (to match the focal length of the pinhole). For the non-comparison photos, I used the 12cm focus, but adjusted ISO and exposure time as needed to produce better lit photos. |
Phone Model: OnePlus 3 | IMX298 (ifixit.com, fair use) |
Desk This was taken at night with two different bright light sources. | UC Berkeley Botanical Garden |
Dim Sum | Cat The cat was just hanging out, and didn't mind posing for a picture. |
I used a bright bicycle light, 400 ISO, and 30 second exposure to draw the pictures. The bicycle light acted like a point light source, and was brighter than all of the background light. Due to the lower ISO and long exposure, the light became like a paint brush on the pinhole camera canvas.
Name | Happy Face |
OK Face | Umbrella |