What is Pinhole Camera?
Pinhole cameras are based on light travelling in a straight line – a principle called the rectilinear theory of light. This device is also known as camera obscura, which means ‘darkroom’ in Latin.
A pinhole camera is a simple camera that forms an image without using a lens or a mirror.
It consists of a light-proof box with a tiny hole in one end and some film or photographic paper on the other end. When light rays go through the tiny hole, it forms an upside-down (inverted) image at the back of the box.
In the picture above, light ray ‘a’ travels in a straight line, passes through the pinhole and falls at ‘a1’ on the screen. Similarly, light ray ‘b’ falls at ‘b1’. Thus ‘b1a1’ is the upside-down (inverted) image of the tree that is formed on the screen.
If you increase the number of holes, the number of images also will increase.
How to Make a Pinhole Camera with Shoebox DIY
- Take an empty shoebox
- Paint the inner part of the shoebox in black color to make it light-proof.
- Cut one end of the shoebox and fix a wax paper or tracing paper over the open end.
- With the help of a sharp pencil or small nail, make a tiny hole at the center of the opposite side.
- Point the tiny hole towards a bright object like candle flame or tree.
- You will see an inverted image of a tree or candle on the wax paper screen.
Principle of Pinhole Camera
- The pinhole camera works on the principle that light travels in a straight line that is rectilinear propagation of light.
- When we open the shutter, light illuminates to form an image on photographic paper placed at the camera’s back.
Pinhole Camera Image Characteristics
- The image in a pinhole camera is upside down (inverted) as compared to the object.
- The image in a pinhole camera is real; hence it can be formed on the screen.
- The size of the image obtained is comparatively smaller than the actual object.
- The image is of the same color as the object.
- Pinhole cameras are based on the fact that light travels in a straight line.
Natural pinhole camera
We can see a wonderful pinhole camera in nature. Have you ever seen the bright spherical patch of sunlight on the ground when you go under a large number of leaves-covered trees? I’m sure you must have seen this.
These patches of light are the Sun’s pinhole images. The tiny gap between the leaves acts as pinholes, groundworks as a screen, and the Sun acts as an object. When the light comes from the Sun passes through these pinholes and makes images (patches) on the ground.
What are the Uses of a Pinhole Camera?
- We can project the image formed by a pinhole camera on a translucent surface for real-time and safe solar eclipse observation.
- To capture the movement of the Sun over a long period of time (a process known as Solagraphy).
- We can use this device for surveillance purposes as they are difficult to detect.
- Pinhole cameras are helpful to observe the reflected image of a dazzling object.
- A pinhole camera is also helpful for the artist to view a scene from a unique perspective.
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