Why does looking at things from a small hole make it more clear?

[scilearner]

Hello everyone,

 

Why do looking at things with one eye closed through a small hole like microscope make the object look clearer. Someone told me it gives less abberation. Then I checked it online and it said different wavelengths converge at different points in a lens. Ok I understand why that would create a blurred image, but I don't understand why looking at objects as the way I describe create less abberation. Thanks

[swansont]

Pinholes give images; the virtue of the small hole is that rays that are off-axis — and would blur the result — are blocked.

 

http://www.howstuffworks.com/question131.htm

[scilearner]

Pinholes give images; the virtue of the small hole is that rays that are off-axis — and would blur the result — are blocked.

 

http://www.howstuffworks.com/question131.htm

 

Thanks swansoft Why does pin hole block rays off axis? I mean light still has to pass through pupil, so isn't it the pupil that can block this?

Edited April 26, 2010 by scilearner

[Cap'n Refsmmat]

The pin hole is small, so the off-axis rays don't go through it. If the pinhole's in the middle of a piece of metal, the off-axis rays strike the metal instead of going through the hole.