Many people like telescopes when traveling, but they have many questions about telescopes, especially the issue of distance. How far can they be seen?
In fact, the telescope has no distance limit, it achieves a close-up effect.
The distance seen by the telescope is related to human vision
For example, the letter on the visual acuity chart: “E” When placed at a distance of 5 meters, people with good eyesight can still see the bottom line, but people with nearsightedness can only see the large “E” in the first few lines, and the bottom line. Still can’t see clearly. A nearsighted person will say that the telescope cannot see 50 meters, and a person with good eyesight will say that the telescope is very good. Can you say that the telescope can only see 50 meters?
The distance seen by the telescope is related to the size of the object
For example, if there is an ant at 1000 meters, if you use a 10 times telescope, it is equivalent to pulling the ant closer to 100 meters, but you still can’t see it. Can you say that this telescope cannot see 1000 meters? If it is a person at 1000 meters, you use a 10 times telescope, which is equivalent to pulling the person closer to 100 meters, you must see clearly. With a telescope, you can clearly see the surrounding mountains of the moon at a distance of 380,000 kilometers, but you can’t see the satellites of the earth that are much closer to us.
The distance seen by the telescope is related to the quality of the telescope itself
For example, if there is a person at a distance of 1,000 meters, you can see it with a 10-fold telescope worth several thousand yuan and a 10-fold telescope worth tens of yuan, and the degree of clarity of what you see is very different.
Two telescopes have the same parameters (multiplier, aperture, field of view, exit pupil distance, exit pupil diameter), and telescopes with exactly the same size and appearance may differ in price by several times or more. This is the quality of the telescope itself ( Factors such as lens coating, lens quality, etc.).
The lens, prism, coating, and structure of the telescope determine the quality of the telescope. The light transmittance of a good telescope can reach more than 90%, and a poor telescope is only 50%-60%.
The distance seen by the telescope is related to the air quality
For example, with the same telescope, the same person observes the billboard at 1000 meters. After the rain, in sunny weather with the sun, you can clearly see the small print on the billboard. In the case of cloudy days without sun and car exhaust and dust in the air, it may not be very clear. Furthermore, if there is fog, that is, there are a lot of suspended particles in the air, and the visibility is reduced, you may not even be able to see it at 5 meters. Therefore, a careful friend will find that the telescope does not have an indicator of distance. As long as there is an infinite object, the telescope can see infinite distance. Planets that are hundreds of light-years away can be seen without a telescope, and we can also see it with a telescope. The moon is far away from us (380,000 kilometers), and we can see it with a telescope. But molecules, atoms, etc., no matter how good a telescope you use, how close you are, you can’t see them.
Therefore, when choosing a telescope, you mainly need to look at the quality, multiple, and field of view of the telescope. You don’t need to entangle the distance!