This school science animation is about a pin hole camera, also known
as 'Camera Obscura'. A pinhole camera consists of a rectangular box, closed
on all sides and having a pin-hole on one of its faces and
a screen on the side opposite to the pin hole.
uses the principle of rectilinear propagation of light.
A Pinhole Camera consists of a small aperture through which
the light passes, a dark enclosure, and a piece of film.
An object placed in front of a Pinhole Camera forms a clear
image on the film without the need for a lens. Because the
aperture is so small (diameter about 5mm), from each point
on the object, only one ray of light may pass through and
then move on to the film. Thus there is a one-to-one correspondence
between points on the film and points on the object.
The following questions are explained in the "animated pinhole camera" are :
1) What is the effect of variation of the distance between the pinhole and the
screen and the object and the screen and the image size ?
2) What happens to the number of
images if the number of pinholes are increased in the pinhole camera ?
3) What happens to the images in the pinhole camera If the number of objects increases ?
4) Why is a blurred and bigger image formed by making the size
of the pin the pinhole camera bigger?
Extra information : Pinhole cameras have infinite depth of field. Everything
from the closest object to the most distant object is in
the same relative focus; objects at a far distance will
be less sharp due to particles in the atmosphere. A pinhole
reproduces a scene just as the eye sees it. While there
is no focus for different planes in pinhole photography,
there is a relation of pinhole to film that gives the maximum
definition and it is this combination of softness with strength
that gives to the pinhole photograph its essential character.
Despite its distant past and apparent simplicity, the pinhole
camera offers several advantages over lens optics, particularly
when resolution is not especially important. These include
i) complete freedom from linear distortion
ii)depth of field from a few centimeters to infinity
iii)wide angular field
The pinhole's light-gathering ability is poor, but this
is largely offset by the high sensitivity of modern films
and television cameras. In addition, pinholes can be used
in the ultraviolet and x-ray regions of the spectrum when
reflecting or refracting materials are not readily available.
Make your own pin hole camera:
1. Punch a hole in the center of the box using the pin.
2. Remove the top of the box. Put a wax paper over the box's
open end to make the screen. Use a rubber band to hold it.
3. Point the camera at a brightly lit object in or outside
the dark room. What do you see on the wax paper screen?
If you are still unclear about the concepts, please refer
the animation .