> a glass of water with a straw inside is a simple example. > you see the straw bent but it is not. > thats what happen with light when it changes the medium it is travelling > (from air to water or through the glass, example). I am not sure about > what happens with pinhole, once there is no medium change. anyone?
I believe that is refraction, where the light bends when it goes from one medium to another. An example of deffraction would be the edge of your shadow. If you look at the edges of a shadow, you will see that it is not a distinct line, but rather a fuzzy transition. In short, when light strikes the edge of an object, it scatters. If you think of the metal around the pinhole as casting a shadow on the film, the edge of the shadow (spot of light from the pinhole) isn't a perfect circle because of diffraction. The edges of the spot of light are blurry, which degrades the sharpnes of the image. Hope that helps, John
