Why can this telescope only focus on very near objects?

In summary, the conversation discusses a challenge with a school's theodolite, where the telescope is unable to focus beyond 7' despite giving a clear image of objects between 3'-7' away. The focus knob still works, indicating that the issue may lie with the eyepiece optics. Possible causes discussed include a curious student scrambling the optics, the eyepiece being removed and re-inserted incorrectly, or a misalignment of the mirrors in the telescope. It is suggested to do a thorough check for any damage or interference preventing movement of the lens, and it is also possible to carefully disassemble the device to investigate further.
  • #1
Harlan
3
0
OK - Here's a challenge. Our school has a theodolite; its telescope worked in the past. Now it suddenly won't focus beyond 7', though it gives a great image of objects between roughly 3'-7' away. The focus knob seems to move freely.

My thought is that the eyepiece optics somehow got scrambled, perhaps by a curious student...but what would cause this?
 
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  • #2
Does the focus knob function? In other words, can you manipulate the focus between 3'-7', or could the focus knob be somehow disengaged from the lens?

Another thought- was the eyepiece ever removed? It's possible some of the elements inside fell out and were re-inserted wrong.

Take it in for repairs?
 
  • #3
I don't know anything about a theodolite, but I do own a telescope. If it uses mirrors it is possible that a sudden jarring could misalign the mirrors. This might not have any noticeable effect on focusing on short range objects, but long range objects could get distinctly blurry depending on the severity of the misalignment.
 
  • #4
Yes, the focus knob still works, and it is a refractor, so no mirrors.
 
  • #5
All I can say is do a thorough check of the telescope and check for any loose lenses, dents, cracks, or any other damage. Other than that I can't say.
 
  • #6
Harlan said:
Yes, the focus knob still works, and it is a refractor, so no mirrors.

In order to focus on distant objects, the lens must move closer to the eyepiece. There could be mechanical interference between the lens and eyepiece preventing movement (which you may be able to feel).

Depending on your comfort level, you could find a clean surface and carefully disassemble the device to see if there's an obvious problem.
 

1. Why can this telescope only focus on very near objects?

The reason why a telescope can only focus on very near objects is because it has a limited field of view. This means that it can only capture light from a small area at a time. Objects that are far away appear smaller and require a larger field of view to focus on, which is why telescopes are often used for viewing objects in the night sky that are relatively close to Earth.

2. What is the maximum distance that this telescope can focus on?

The maximum distance that a telescope can focus on depends on its design and capabilities. However, most telescopes are designed to focus on objects within our own solar system, such as the moon and planets, as well as objects within our own galaxy. This can range from a few hundred thousand to several million light years away.

3. Can a telescope be adjusted to focus on objects that are further away?

Yes, some telescopes have adjustable focus mechanisms that allow them to focus on objects at different distances. However, this may come at the expense of image quality, as the telescope's optics may not be optimized for distant objects.

4. Why are telescopes not able to focus on objects in other galaxies?

The main reason why telescopes cannot focus on objects in other galaxies is because of the vast distances involved. The light from these objects is incredibly faint by the time it reaches Earth, making it difficult for telescopes to capture and focus on. Additionally, the resolution of even the most powerful telescopes is limited, making it challenging to capture clear images of objects in other galaxies.

5. Are there any telescopes that can focus on objects in other galaxies?

Yes, there are telescopes that are specifically designed and equipped to observe objects in other galaxies. These include space-based telescopes like the Hubble Space Telescope, which is able to capture high-resolution images of distant galaxies. However, even with these advanced telescopes, the image quality may still be limited due to the vast distances involved.

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