Introduction
Ibn al-Haytham, an Arab scholar discovered the world’s first pinhole camera. He used a camera for projecting an image onto a flat surface with the help of light.
A pinhole camera is one of the most uncomplicated and elementary cameras. It uses a tiny opening or hole to focus light rays on a single point. An inverted image is always formed using this setup. These cameras have infinite depth and simple construction methods. These cameras are also called camera
obscure.
How Does The Pinhole Camera Work?
It works on a very simple principle. Pinhole cameras rely on the fact that light obeys the rectilinear theory of light. The pinhole camera blocks the undesired rays when light passes through it. Because of this, clear image formation takes place.
Imagine yourself inside a dark room with a small opening on the wall you are facing. When someone incident light from outside, we can see a thin light ray coming into our room. If there is any movement in the source, we will observe changes in the direction and even in the intensity of light.
Imagine a light-proofed small box except for the small pin-sized hole. And this setup also has a film that captures the light rays. This film inside the film only records the image. The pinhole in this setup acts as the lens. In a regular camera, a convex lens helps to register more light. This light is then focused majority on the small area. Because of this, exposure time is also reduced.
It also has a drawback that exposure has to occur for a prolonged period. As the pinhole limits the amount of light entering the box.
To get a well-focused image, the diameter of the pinhole has to be 0.236 mm. On increasing the size of the hole, we observed a decrease in the image’s sharpness. Also, the image ends up being thick and blurry. Because the amount of light entering the box leads to increased light distribution.
Construction Of Pinhole Camera:
Items required
⦁ Pencil
⦁ Empty Box
⦁ Knife
⦁ Ruler
⦁ Wax Paper
⦁ Tape
⦁ Blanket
Procedure:
⦁ Use a pencil to punch through the box at one of the ends of the box.
⦁ Use a knife to cut a square at the opposite end of the box right across the hole. The Square should measure 2 inches on each side.
⦁ Use a scissor to cut a square of wax paper (3 inches) on each side.
⦁ Place the wax paper over the square you made in the box. Use tape on the edges of the wax paper to fix it.
⦁ In the dim lightroom, place the box and turn on the lamp.
⦁ Use a blanket to cover your head and pinhole camera. Make sure that the end with the wax paper is towards you and the one with the pinhole opposite to you.
⦁ Now hold your pinhole camera at arm’s length and aim it at the lamp. Keep it steady to see an upside-down image of the lamp.
Pinhole Camera
A few of the best brands of pinhole cameras are DIY and 4M. Its technical specifications include:
1. Weight ranging from 40 grams to 250 grams.
2. No battery needed.
Image Characteristic
⦁ A real image formation takes place.
⦁ Formation of an inverted (upside down) image takes place.
⦁ The size of the image obtained is smaller than the actual object.
⦁ The image formed has the same color as the object.
Uses Of Pinhole Camera
⦁ It helps in capturing the movement of the sun over a long period of time.
⦁ They are helpful for surveillance purposes.
⦁ A translucent screen helps in observing the image obtained of the solar eclipse.
⦁ This device helps artists view scenes from a unique perspective.
⦁ It helps us to view the images of various objects such as trees, buildings, etc.
Conclusion
Camera obscura and pinhole camera are quite similar in nature. In practice, we will find that camera obscura uses a lens rather than a pinhole. It allows a larger aperture than a standard pinhole camera. To produce a clear image, aperture size has to be 1/100th of the distance to the screen.
One of the disadvantages of the pinhole camera is of ‘Circle of Confusion. It’s the smallest circle that one can resolve from a perfect point of light.
For a digital camera, if the circle of confusion is smaller than the pixel size you get a clear image. Image is not limited to the resolution of the pinhole. But the sensor used. While with a larger circle of confusion, the lens limits the effectiveness of the image. Megapixels present in the sensor do not matter.