1 Eyes vs Cameras

1. Light emanates off every point of an object outwards in every direction
   1. That’s why we can all look at the same spot on the same object and see it
   2. Light is leaving from that point/spot on the object and entering each of our eyes / cameras

What is a camera?

Let’s design a camera

1.1 Idea 1: put a piece of film/sensor in front of an object

• the sensor records irradiance
• Do we get a reasonable image?

1.2 Idea 2: Add a barrier to block most rays

1. Pinhole in barrier 障碍物

2. Only sense light from one direction.

3. Reduces blurring.

4. Instead of a pupil瞳孔, the camera has a small (adjustable) aperture **孔/**光圈 that light passes through

5. Shrinking the aperture - diffraction

   

   1. A larger pupil/aperture allows light from a larger area of an object to hit the same cone causing some amount of blurring

      

   2. If too small, not enough light enters and the image is too dark/noisy to interpret

      • In addition, light can diffract 衍射 (instead of traveling in straight lines) distorting the image

• Largest Pinhole Photograph: Diameter: 6mm

1.4 pinhole camera