A camera is similar to the human eye, but one is superior to the other. The other day I was looking at a picture I had taken of a sunset at Ocean Beach in San Francisco. I found my eyes had to wander over the print to take in all the detail. This made me wonder, what exactly are the similarities and differences between the human eye and a camera. Here’s what I found out:
- Structurally, our eyes and cameras are very much alike. Light rays pass through a lens, and are focused on a light sensitive material. For digital cameras this material is a semi-conductor device, for our eyes the material is the retina.
- Notice in the picture how both flip the object upside down – this is a result of light passing through a small hole. In the eye this hole is the pupil, in the camera the hole is called the aperture.
- For cameras, turning the object back upright isn’t a problem – just turn the resulting photo back upright! For eyes, the optic nerve carries the light signal to the brain, which automatically flips the image upright. Clever brain.
- For our eyes, this means: What we really “see” is our mind’s reconstruction of objects based on input provided by the eyes — not the actual light received by our eyes.
- Most current digital cameras have 5-20 megapixels. With 20/20 vision, the human eye is able to resolve the equivalent of a 52 megapixel camera.
- However, only our central vision is 20/20, so we never actually see that much detail in a single glance. Away from the center, our visual ability decreases dramatically. At the edges, we only detect large-scale contrast and minimal color. (see photo below) Aha! That’s why when I was looking at my beach sunset photo, I had to scan my eyes over it to take it all in!
- One last difference is the way each focuses. A camera focuses by changing the distance between the lens and the back of the camera. Our eyes focus by changing the actual shape of the lens.
All in all, the human eye outperforms most of the cameras any of us could afford. The speed with which the pupil adjusts to varying brightness, the speed of focus, and the resolution are all integrated and function much quicker. But most importantly, a camera isn’t happy to see a warm sunset or a smiling child.