Chapter 25, Problem 8Q

To determine

Why you can see clearly when you move your head with your eyes open unlike the blurred image formed in a camera when you move the camera while the shutter is open (since human eye and camera are much alike).

Answer to Problem 8Q

Solution:

When we move the camera with open shutter, the image position formed on the film changes. The new image formed will be at a different position than the old and it causes the new image to overlap the previous image, causing a blur in the final image.

Explanation of Solution

While the camera shutter is open, the light entering the camera lens contributes to a single image. When we move the camera with open shutter, the image position formed on the film changes. The new image formed will be at a different position than the old and it causes the new image to overlaps the previous image, causing a blur in the final image.

While in the case of eye, continuous image formation is done by the nervous system, so the images will not “build up” on the retina and overlap with each other. Your brain “refreshes” the image from the retina about 30 times a second. More simply saying, brain and retina work together in the similar manner how a motion picture camera and film work together, and which is entirely different from how a still camera and film work.