Why does a lens automatically produce perspective?

In summary: Hello everyone,so reality is 3D and lenses, cameras, are trying to reproduce that 3D reality on a 2D plane. Objects that are farther away from the camera appear smaller than those that are closer, and foreshortened. Perspective also changes depending on the focal length of the lens. Telecentric lenses do not introduce perspective distortions, but they do change the perspective of the object in relation to the camera.
  • #1
fisico30
374
0
Hello Forum,

can anyone explain why a camera, a lens, automatically creates perspective in an image?
Is it explainable with ray tracing?

thanks
fisico30
 
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  • #2
What do you mean by "creates perspective"?
Edit: I guess you could say it's simply an intrinsic result of focusing light.
 
  • #3
I don't know what you mean by the lens creating perspective. The perspective is in the scene, the lens focuses the light from the scene, the camera records the light patterns.
 
  • #4
fisico30 said:
Hello Forum,

can anyone explain why a camera, a lens, automatically creates perspective in an image?
Is it explainable with ray tracing?

thanks
fisico30

If you are referring to 'depth perspective', the answer is that magnification varies with object distance. In terms of ray tracing, put two objects of equal size at the front-and-rear edges of the depth of focus and see what the image heights are.
 
  • #5
Hello everyone,

so reality is 3D and lenses, cameras, are trying to reproduce that 3D reality on a 2D plane...

I have recently read about foreshortening in perspective. Depending on the distance, point of view and focal length of the lens, we can get certain geometric distorsions in the picture; parallel lines seem to go to the vanishing point and the farther the object the smaller it is...
Automatically, a camera introduces all these artifacts of perspective (sometimes they are exaggerated too). In wikipedia, perspective has two attributes:
Objects appear smaller as their distance from the observer increases;
Foreshortened: the size of an object's dimensions along the line of sight are relatively shorter than dimensions across the line of sight;

Telecentric lenses, which I mentioned some time ago, don't create perspective distorsions...
for example a cylinder that lies along the optical axis seems to converge to the vanishing point. The rear of the cylinder appears smaller and the body of the cylinder appears oblique since parallel lines seem to converge to the vanishing point...

fisico30
 
  • #6
An artist, when drawing a scenary, uses the laws of perspective to recreate the same effect that we have when we look at the real 3D world...

It seems that lenses and optics somehow do the same...is that true?
 

1. Why does a lens automatically produce perspective?

A lens produces perspective because it is curved and refracts light. When light passes through a curved lens, it is bent, causing objects to appear closer or farther away depending on the angle of the lens and the distance from the object to the lens.

2. How does a lens create depth in an image?

A lens creates depth in an image by focusing light from different angles onto a single point on the camera's sensor or film. This results in objects appearing larger or smaller in the image, giving the illusion of depth.

3. Can any lens produce perspective, or only specific types?

All lenses, regardless of their type, have the ability to produce perspective. However, the amount of perspective produced may vary depending on the curvature and focal length of the lens.

4. Is perspective only created by lenses in photography, or can it also be seen in other forms of art?

Perspective can be seen in many forms of art, including paintings, drawings, and sculptures. In these mediums, artists use techniques such as foreshortening and vanishing points to create the illusion of depth and perspective.

5. Is there a limit to the amount of perspective that can be produced by a lens?

There is no definitive limit to the amount of perspective that can be produced by a lens, as it depends on factors such as the curvature and focal length of the lens, the distance between the lens and the subject, and the size of the sensor or film. However, as the distance between the lens and the subject increases, the amount of perspective produced typically decreases.

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