Eye vs Telescope: What Limits Our Sight?

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In summary, the eye can see to the edge of the universe if there's a bright enough light. The difference between the eye and telecope is three things- sensitivity, magnification, and spectrum.
  • #1
physickkksss
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Hey guys, just wondering what limits how far an eye can see...

I understand how an eye works. Light comes though the lens and focus on the retina, which goes to brain for interpretation, etc.

And I understand the workings of different types of teloscopes. In different ways they gather lots of light and focus it through the eyepiece. I think essentially they collect more light for the viewer.


But is that all that is different?

If our eye was as wide as the front lens of a teloscope, would our eyesight be equivalent to a teloscope?
 
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  • #2
The eye can see to the edge of the universe if there's a bright enough light.

The difference between the eye and telecope is three things.

1) sensitivity aka light gathering power.
The scope has two advantages. Big aperture and time integration. It can gather more light and can bring in light over hours to fill in even dimmer images.
2) Magnification. Saturn looks like a dot to the eye. The scope sees rings and moons. That's the most striking difference.
3) Spectrum. Instruments on the scope can see things the eye can't like UV, IR, radio or even Xrays.

If the eye was as big it could do 2 and some of 1 but not 3.
 
  • #3
To answer the specific question of how "far" the eye can see. There is no limit.

What is the minimum amplitude of radiation that the eye can detect is a different question.
 
  • #4
LostConjugate said:
To answer the specific question of how "far" the eye can see. There is no limit.

What is the minimum amplitude of radiation that the eye can detect is a different question.

Is it worth noting that time (i.e. having enough of it for the light to cover the distance) is a limit?
 
  • #5
Fewmet said:
Is it worth noting that time (i.e. having enough of it for the light to cover the distance) is a limit?

Asking how far can you see is like asking how far can your car can travel. How much gas do I have? How much time I have?
 
  • #6
There is another very important factor about a telescope. The diameter is much greater than your eye and so is the 'resolving power'. That is to say, you can see much more detail because of the larger aperture. The extra resolution is at least as important as the extra light-gathering of a big diameter lens.
 
  • #7
It is a matter of energy conservation and symmetry of space.

The total energy from the light emitting source is spread over the surface of sphere of radius r = distance from the object. A larger lens is tapping into a larger portion of this sphere.
 
  • #8
The question is flawed insofar as one must specify the resolution at which one intends to observe said objects in order to receive a reasonable answer.

To observe a photon from a distant quasar with the naked eye is possible (not that you would know that you had observed it); observing it with any significant resolution is impossible without an outstanding optical system.

Claude.
 
  • #9
I think there is no way of determining the source of just one photon because any optical system relies on diffraction (that is ANY optical system) to form an image. Diffraction involves a (large) number of photons for an intensity distribution to reveal the direction of the source. You would have no way of distinguishing just one photon coming in from the side from one arriving on axis.
 
  • #10
I think that was his point sophie. That you CAN detect photons from very distant sources, but that one single photon or even a few cannot form an image. You "wouldn't know you say it".
 
  • #11
Drakkith said:
I think that was his point sophie. That you CAN detect photons from very distant sources, but that one single photon or even a few cannot form an image. You "wouldn't know you say it".

My point was that there is no "outstanding optical system" that could tell you. All you would know was that a photon had arrived from somewhere. It takes several of them to give any idea at all about their source (if it is a single source even).
 

FAQ: Eye vs Telescope: What Limits Our Sight?

1. How does the human eye compare to a telescope in terms of sight?

The human eye and a telescope both have the ability to gather and focus light, but the eye has a much lower resolution compared to a telescope. This means that the eye is limited in its ability to see fine details and objects that are far away.

2. What are the physical limitations of the human eye that affect our sight?

The human eye has several physical limitations that affect our sight, such as the size and shape of the eye, the number and distribution of photoreceptor cells, and the presence of the blind spot. These limitations can impact how much light is gathered and focused and how well we can see fine details.

3. How do telescopes overcome the limitations of the human eye?

Telescopes are designed to gather and focus light more effectively than the human eye. They have larger apertures and multiple lenses or mirrors that help to gather and focus more light. They also have better resolution, allowing us to see finer details and objects that are much farther away.

4. Can technology improve the limitations of the human eye?

Yes, technology such as glasses, contact lenses, and laser eye surgery can improve some of the limitations of the human eye. These methods can help to correct vision problems like nearsightedness, farsightedness, and astigmatism. However, they cannot improve the eye's overall resolution or expand its range of vision.

5. What are the limitations of telescopes in terms of sight?

While telescopes have a much higher resolution and can see farther than the human eye, they also have their own limitations. Factors such as atmospheric distortion, light pollution, and technological constraints can affect the quality of images produced by telescopes. Additionally, telescopes are limited by their size and the materials used in their construction, which can restrict their ability to gather and focus light.

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