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Between the sense of sight and photography... Common advantages and essential differences

A comparison between photography and the sense of sight may be possible and justified because there are some common advantages between them, but the fundamental differences take up a larger space between the two fields, which gives each of them a unique view of the world around us.

With a superficial and quick look at things, we think that the human eye and the camera are completely similar, when in reality the differences greatly exceed the similarities.
The main similarity between the eye and the camera is in their use of the lens system together to form an image on a surface that senses light.
Our viewing of a scene is based, in fact, on the formation of two accurate, upside-down images on the inner back surfaces of the eyes - the retinas - and these are light-sensing layers. It is connected by the optic nerves to the brain, and it consists of mosaic receptor cells.

The image is formed on the retina by means of a lens system. This is because the light that reaches the eye is refracted by the lens and passes through a transparent liquid called the aqueous humor. It comes from an opening called the pupil, then it is further refracted by the crystalline lens.
The main task of this lens is simply to adjust the lens system to focus on targets located at different distances. This process is known as eye accommodation (accommodation) and is achieved by a muscle called the ciliary muscle (ciliary muscle) that adjusts the focal length of the lens and it does so by changing the shape of the lens. A major difference between the two human systems And photography. Then, after leaving the lens system, the light passes through a transparent liquid called the vitreous humor, where it reaches the retina and is captured by the receiving cells there.
There are two main categories of receiving cells:
Cone cells respond to strong and normal lighting levels, and they are responsible for color vision and are mainly concentrated towards the center of the retina.
And in the very center, in the area known as the fovea, there are only cone cells that are densely accumulated there. It is the area responsible for sharp vision, which is located in the middle of the visual field.
As for the rod cells, they are responsible for light light. They do not produce color sensations at all, and they are more dispersed, as they are most located towards the edge of the retina. For this reason, we find that in the case of soft light, when the rod cells work alone only. Viewing is much less intense than it is under normal circumstances.
This equal distribution of cells means that the image becomes corrupted towards the edges, where the cells are less dense, given that the total viewing field of the human eye is very wide - up to 180 degrees horizontally - but the viewing edges are only useful for observing movement.



As for the camera, on the other hand, the resolution (resolution) is almost the same in the entire image area. In the case of human vision, in order to make a detailed picture of the scene, the eyes and head make an exploratory movement.
In this way, the acute central region of the eye - the fovea - can see all parts of the scene separately.
Although the image is formed upside down, this does not cause problems, because the brain corrects the information sent from the eyes so that it does not
We see the world upside down.

It should be noted that human vision is able to make a number of facilities for viewing in different conditions, and what is most important in this regard is adapting to darkness, because the use of different cells and the adjustment that occurs in the pupil scale allow the eye to adapt to a range of light levels, such as the iris of the eye. (ivis), which is the colored part of the eye, changes so that the dilation of the pupil increases in soft light conditions and decreases in bright light conditions - in a manner similar to a lenticular aperture -

However, the process of adaptation may need some time if the difference in luster is very large, because there is another mechanism that takes its course - sorting out a chemical substance called visual purple, which gives the retina more sensitivity - from here, the eyes that become accustomed to the weak light in A dark room - those eyes that have become accustomed to the darkness - collapse when suddenly confronted by daylight. Then when entering the darkness, acclimatization may need about half an hour sometimes!
Hence, in order to help the eye adjust to the softer illumination of a camera's focusing screen, all extra light should be eliminated by the use of an eyepiece cup, or collapsible head. Or focus cloth, the screen looks brighter in fact.

The film does not include coping energies. When photographing a scene, exposure is usually a compromise between different tonal gradations, and details may be lost in shadowy or bright areas. As for the eye, for its part, it moves from one area to another, adapting relatively to each different light level.

One of the advantages that distinguishes photography from human vision is that light has a cumulative effect on the film. In the case of very weak light, it is possible to make the image over a period of a few hours, and the element that limits that is mutual failure. As for the eye, a certain minimum amount of light must fall. The placement of cells during a specific period of time - approximately a fraction of a second - and if a sufficient amount of light is not received during this period, the eye cannot see.
Then we find that most of the cameras are limited to viewing one single view, while human sight is based not on just one view, but two, then the two images that the brain receives come together and are linked to the viewing angles in the eyes to give a sense that enables us to judge close distances with great accuracy.

We see from the foregoing that human and photographic systems are based on different views of the subject and work in different ways to record it, and there are many other differences regarding colors in particular.
The fact that the differences between the way we view and the way the camera records is one of the features that make photography exciting and fun⏹