Why do all lenses, including those in the human eye, invert the image? Or are they? It’s much easier to understand than you might think.
Light is reflecting off objects around us, and although we’re used to seeing graphs with light represented as a line, it’s a bit misleading.
Light rays are rarely reflected in one direction
If you shine a laser pointer at a mirror, you can draw it as a simple line because a straight beam of light is being emitted from a pointer and reflected off a mirror, but the sun is not an object. laser pointers, and most objects do not produce perfect reflections; They scatter light in all directions. If you shine a laser pointer at a tennis ball, you will be able to see the point of light from anywhere on this side of the ball because the light radiates in all directions.
Why are lenses needed?
Everyone knows that cameras require a lens to focus light, but let’s see why. If you have a camera sensor or a piece of film without a lens, it will pick up light rays from all directions. Every part of every object in the sensor’s field of view will illuminate the sensor at the same time. The sensor will receive a lot of light, but every pixel will have roughly the same reading.
How a pinhole camera works
Pinhole cameras work without any lenses, but their images are still flipped. They work by blocking the majority of light rays hitting the sensor from all angles and instead only allowing rays to enter from a single point. Light waves emitted from the top of an object will be intercepted when hitting the top of the sensor, but will hit the bottom of the sensor. The waves coming from the bottom of your scene will be blocked from the bottom of the sensor, but will reach the top. And remember that all these diagrams are drawn in two dimensions, but this is happening in three dimensions: up, down, front, back, left and right.
Another way to understand how light enters the camera
If you still don’t understand this, imagine you are looking through a peephole in the door and you want to see the ceiling on the other side of the door; you will have to bend down and look up to see it because the light from the ceiling will be blocked from your eyes. To look down, you will have to move up to a higher position. To see left you need to scroll right and to see right you need to scroll left.
Why lenses are better than pinhole cameras
Pinhole cameras don’t let much light into the camera and they don’t produce very sharp images because they don’t focus the light rays, they simply block most of them. To focus light rays, we can use a lens to receive more light rays and focus them on a sensor. This produces a brighter, sharper image, but doesn’t change the fact that light rays coming from above the lens are hitting below our sensor and rays coming from below our scene. We’re showing above.
Inference
The lens itself is not inverting the image. Light rays reflected from objects in the upper part of the scene will be blocked by the camera or lens cover (in the case of pinhole cameras) or focused (in the case of lenses) and only reach the bottom of the sensor, film, or the back of our eyes.
