Why is the lens round, but the picture taken is square?

Why is the lens of the camera round, but the photos taken are square? This is a very interesting question. It involves several aspects of knowledge.

Scientists know that our common photo specification is 3:2, which is different from the imaging of the lens.

This is the circular picture imaged by the lens, and it is also the specification for recording photos.

If a large exposure range is forced, the photos will have dark corners.

The darkness of the photo is caused by the lack of field of view of the lens.

Why are lenses round instead of rectangular? This is because the lens is composed of a lens with a truncated part on the spherical surface, and the central point is used as the coordinate origin to symmetrically converge light for imaging.

Although the picture we see in the book is like this.

But the actual lens is like this.

If the origin of the mirror is symmetrical, but a horizontal line is symmetrical, then the lens becomes a part of the truncated cylinder, and what you see is not a clear image, but a one-dimensional information like a bar code.

Semi-cylindrical lens

Lose the image of the y axis

The cross section of the lens is naturally circular. At the same time, the treatment and use of mirrors, cutting or rotating zoom are all good choices. And there is a very important reason. In many previous cameras, the lens was fixed in a spiral, and there was no accurate direction. The angle of the picture cannot be guaranteed by using square or other special-shaped lenses cut like spectacles.

Then why is the photo square? This is because, like other traditional carriers, film and photographic paper are left over from historical cutting. In the silver salt photography era of film/photographic paper, both film and photographic paper were cut from large pieces of material. The most reasonable plane cutting method is regular quadrangle. If it is cut into a circle, it will produce a lot of scraps, which is not conducive to collection and binding.

This is the rest of the circular cut.

In fact, if the picture content is heavier than the recording cost, the photo can also be round, so as to make full use of the lens shooting content. Such as space exploration or photomicrography. Only when it is displayed on paper or a monitor, a rectangular box is put on it to facilitate our management and browsing.

Microscopy, the effective picture is round.

After historical evolution and elimination, we have seen this phenomenon. The lens is round and the photo is square.

This article is taken from Old North Wind Writing.

Hope to help the landlord!

I hope my answer is helpful to you.

From the principle of pinhole imaging, we can know that the result formed by the camera through the lens is actually round.

But the following photosensitive elements are all square, which means that a square range in the circle is obtained through these photosensitive elements, and other ranges are ignored, so the result is square.

The lens only transmits light. What is the original scene and what is the scene passing through the lens? Note that it is not round.

However, only light passes through. If you want to "fix" this light (that is, the image), you need a receiver. For the camera, the film and CCD are made into a square, that is to say, only the image of this rectangular part is kept, and all other images are given up.

Because not all the light entering the lens is used for imaging, we only take the light in the middle square area for imaging and image it on film or CCD.

If you ask, why not image all the light entering the lens on film or CCD? Then I will tell you the following reasons:

1, people are used to looking at square pictures

2. The image quality of the lens edge is obviously worse than that of the central part, and there will be aberration.

If you don't want to waste the light entering the lens, you have to waste the film, because the film can only be square.

Do you still think the circle chart is necessary?

If you want to show more content in the photo, you can shoot farther with (1) and (2) use a shorter focal length. It is not necessary to use all the light passing through the lens to image.

If you use an 8 mm fisheye lens, its image will be round. But the situation is just the opposite, and the upper corner of the film or CCD will be wasted.

In the process of a long time ago, today's production principle is to fix the glass on a shelf, and then study the shape of polished glass by rotating it. Moreover, the zoom a long time ago was external zoom. We can see a person holding a camera to rotate the lens, change the structure of the lens group and, of course, zoom. If you use a square lens, you can't turn it around.

Second, let's take a look at why the photos taken by the original lens. It's actually very simple, because the paper you put in is, that is, the negative is square. Then the photo you took is of course square. The development of negative film also promoted the development of positive film industry. The negatives must have a fixed proportion. If there is no fixed scale, different businesses cannot be universal.

But with the development of our science and technology, almost all of them quit. Our eyeballs have replaced digital cameras, which is a technological progress. The proportion of camera images has also broken through the previous restrictions. Now, it is not difficult to produce square lens cameras, but we have all seen them. It is unacceptable for a round camera to become square. The square camera has no advantages and good functions, and operators will not easily put it into the market.

First of all, this is related to the manufacturing history of the camera. As we all know, due to the influence of early technology, lenses are all made of glass fixed and rotated, so it is better to process round glass lenses than square ones.

Second, the early lens zooming was all external zooming, and the focal length could be changed by rotating the external zoom ring, but the square lens could not achieve external zooming.

Third, the early imaging was film imaging. Film negatives were all square, so they were all square. Square negatives were also the industry standard at that time.

Fourth, the camera has been digitized. With the progress of science and technology, it is no longer a technical problem to make a square lens. Everyone has long been used to a round lens. If there is no special progress in square lenses, people will not easily switch to the existing round lenses.

Fifth, people's preference for circles is better than other shapes, which can also be understood as the popularity of circles from an aesthetic point of view.

Sixth, if the circular lens takes circular photos, and the paper photos are not easy to save and store, it is hard to imagine that dozens of plane photos are stacked together, and all the photos have no concept of up, down, left and right. Is it inconvenient for you to look at photos? No matter how you arrange it, you can't find a consistent direction!

I believe the above points are enough to explain why the lens is round and the photos taken are square!

This question is very interesting. I struggled with it when I was a kid. I will understand after studying optics. For the sake of simplicity, I will try to make it simple. I can add something unclear.

When an object receives light, it will diffuse (that is, randomly scatter). Light from any point on the object will be reflected to the whole plane on the lens (this is very important, otherwise it will not be imaged). A lens can be understood as a convex lens, which integrates diffused light from any point into a point behind the lens. This is the function of convex lens. When countless points are integrated, the whole object is restored. After reading this principle, we know that the imaging principle has nothing to do with the lens shape, but only with the focal length consistency of the lens. (That is, this lens must be all or part of a complete convex lens. For example, if you cover a part of the lens, be sure to cover the inside of the lens when you cover it. If you cover it outside the lens, it will think that it is an object instead of a cover. Why must the lens be round? First, because it is made by grinding the spherical surface during processing, it does not need to be cut again; Second, the circle can maximize the area, increase the imaging pixels, improve the light transmittance and increase the brightness of the image (you don't want the photo to be dark).

Hello, I'm glad to answer this question for you. I can't speak Mandarin well. Please forgive me. As for why the lens is round, the photos taken are square, because the lens must be round to adjust the focal length and aperture conveniently. This is the formula of telescope invented by astronomer Galileo hundreds of years ago. The circular lens can maximize the imaging area and output images through the square frame set inside the camera, while the square photo is based on people's traditional visual habits of images. I hope my answer will satisfy you.

To answer this question, we need to know the structure of the camera first. General SLR cameras are composed of lens, aperture, reflector, shutter, five-pointed star, focusing screen and photosensitive elements. How did a photo come from? First of all, when we press the shutter, the light enters the camera from the lens, passes through the aperture, and reaches the mirror (at this time, the mirror will be lifted), and the light enters the photosensitive element, that is, the coms chip, which is a board with a square structure. When colorful light enters the chip, the board will convert the optical signal into an electrical signal (analog-to-digital conversion), and finally form the photos we get. Then why did we finally get a square photo? A chip is like a printer, and the size of the cut picture can only be the size and shape of the chip. It is worth mentioning that the size of this chip also determines whether the camera comes from Quan Huafu or Quan Huafu, and the price of the camera will vary greatly. Professional SLR cameras are generally chips from Quan Huafu. Now you understand why the lens is round. Is the photo really square? If you don't know, please keep asking questions. Thank you for reading.

1. The lens has a focus ring and a zoom ring, which are round, easy to operate and ergonomic.

There are several groups of convex lenses and concave lenses in the lens, so a circle is needed for better light transmission.

3. The circular lens is installed in the circular lens barrel, which is convenient for connection and disassembly with the machine body.

The above answers why the lens is round from the use and physics.

Why are all the other photos square? In fact, some of your shots are also round. For example, the fisheye lens is round and surrounded by black. Why do you think the photos are square and in line with everyone's aesthetic habits? The other is for the convenience of composition.

The physical reason is that the earliest film is square, and now the photosensitive element is square.

I hope you can understand my answer.

It can also be rectangular [covering face] [covering face] [covering face]