A desktop 40x telescope can see a person many kilometers away

I probably know which product you're asking about, and if we sell it.

This?? Let's first explain the issue of viewing and multiples.

40 times, first of all, let's assume that the air is very good (which is not the case in real life), so how far do you feel that you can "see a person clearly"?

Suppose that you feel that the appearance of 50 meters is relatively clear, then let's calculate, this desktop (tripod) product is 40 times, that is, it can bring people at 2000 meters closer to a distance of about 50 meters.

However, in theory this is the case, in practice it is a bit different :)

The first is the air condition, generally 2000 meters, the urban environment, that is, two kilometers, many, many times, the air is not so good. Basically, my experience is that if the air does not affect the quality of the observation image, it is only within 600 meters, and if you are far away, you can find fog more or less with a telescope. Therefore, at a distance of 2000 meters, if you want to observe clearly, the requirements for the air environment are very high (people who use telescopes will find that the air environment is very polluted now, which is the reason).

In addition, in terms of multiples, the desktop type, this multiple range is relatively large, because there is a tripod. But for observing the scenery on the ground, it is generally the highest and the highest, and in my experience, when looking at the scenery on the ground, the image quality begins to decline significantly when it exceeds 40 times, because the air begins to boil, and when it starts at 60 times, it makes no sense. Therefore, in fact, the ground high-power fixed observation, that is, with a desktop telescope, is a more suitable multiple, which is about 30, and this 40 times is a little high, which is the only fly in the ointment of this product.

In other words, you can't expect it to be as close as you are to 50 meters, because 40 times, when you look at the distance, you will feel the air boiling slightly, which also has some impact on the observation.

It is very unprofessional to say how far a telescope can see, because the naked eye can see billions of light-years of stars.

It can distinguish the size of the license plate number, and if you have good eyesight, you can see it from a distance of about 30 meters.

Theoretically, you can multiply the multiple of the telescope by a distance of 30 meters.

However, the volume of the 30*60 telescope is very large, and it is basically impossible to hold a telescope that exceeds 20 times, because the slightest shaking of the magnification is too high will also be magnified, and it is impossible to see the details clearly in a shaking environment. Telescopes of this magnification and aperture must have a tripod to use, and if you can hold it, it is definitely a fake counterfeit that can be seen clearly!

It is also impossible to make the magnification of the telescope too large, and the limit multiple is generally twice the number of aperture millimeters. Some toy astronomical telescopes of several hundred dollars claim to be up to 600 times, but in fact, this multiple is quite blurry and dim, and nothing can be seen at all.

The limit multiple of astronomical telescopes of tens of thousands of yuan is also about 5,600 times, and 200 times for ordinary household ones is already good.

The use of telescopes is also subject to environmental constraints, the farther the distance, the greater the multiplier, the more susceptible to air disturbances, and the brighter the brightness. And limited by the quality of the telescope, so the actual number will be far worse than the theory, theoretically 30 times can see the license plate of 900 meters, but the actual use of 5, 60 times the astronomical telescope can also see more than 500 meters of license plates, to see the 1000 meters of the license plate of the telescope volume diameter will not be less than 150, and the price should be tens of thousands of yuan!

Let me first ask the landlord a question, how far can the naked eye see? Yes?

I'm ashamed to say that I can't answer. With the naked eye, the Great Andromeda Nebula (actually a galaxy, M31) can be seen 2.2 million light-years away, but it is powerless against an asteroid that is only a few astronomical units. It is obviously unreliable to have to give a number.

They are all optical instruments, and this is true with the naked eye, and astronomical telescopes are no exception, which cannot give an observation distance. Generally speaking, the measure of a telescope's ability to gather light is the ultimate magnitude, and popular telescopes are generally in the equivalence, that is, they can see objects that are hundreds of times fainter than the naked eye.

As for magnification, the answer is that if you want to brush the magnification, there is no problem with how high the magnification is.

In the Galileo era, in order to eliminate chromatic aberration, the telescope was once made more than ten meters long, and if today's ordinary eyepieces are used, the magnification of tens of thousands of times can be easily obtained. However, the famous Hubble telescope has a magnification of only 800-1000 times. Comparing the two, it is obvious that the magnification is meaningless.

Generally speaking, the magnification of a popular telescope is about 100 times, and no matter how high it is, it will be the opposite. In my observations, more than 95% of the time I use eyepieces with minimum magnification, the field of view is large, it is easy to find celestial bodies, and the deep-sky celestial bodies are bright. As for **As long as the multiplier is used as a selling point, I personally suggest that these merchants are unreliable, and it is better to find another place.

In order to see the figure two kilometers away, we need to calculate the aperture and multiplier of the telescope.

Known observation distance: 2000 meters.

According to the resolution = wavelength of light of the telescope, megavolts can be calculated to calculate the aperture of the telescope:

times times 1 times 2000 1000 = m$

The magnification of the telescope is known to be: 20x.

Based on the magnification = object distance focal length, the focal length of the telescope can be calculated:

2000 20 = 100 meters.

According to the resolution = light wavelength telescope focal length amplifier large multiple), the aperture of the telescope can be obtained:

times 1 times 100 = m$

Therefore, in order to see people and objects at a distance of 2 kilometers, it is necessary to use a telescope with an aperture greater than one meter and a magnification greater than 20 times.

I am a distributor of a military optical manufacturer, and the condition you mentioned is "2000 meters to see people's faces clearly", I think the air conditions in most areas cannot meet this requirement.

In fact, it is a military desktop old outpost mirror, with its 40 times the look, the actual nuclear Chang is equivalent to 50 meters away with the naked eye, the expression of the face should still be unclear. Gender can only be barely seen from behavior. What's more, this is only theoretical - also take into account the turbidity of the air (this is for sure, air that looks good to the eye will significantly enhance the fog when viewed with a telescope).

In fact, not to mention whether you can see your face clearly, for most cities, 3 kilometers away, it is a white expanse.

So Zhiling said, in fact, this problem has nothing to do with the telescope, has nothing to do with the aperture of the telescope, and has nothing to do with the multiple (because on the ground, I have experimented, no matter how high-end the high-magnification desktop telescope, to see a few things outside the Gongwei family, it is meaningless to start with 60 times, because at 40 times, the air is turbid, so the military kind is also used up to 40 times - to make a high multiple, it is easy, but there is no way to use it.

And simply pursuing high multiples is precisely a common reason for being deceived. Now the market is very chaotic, inferior and counterfeit products, accounting for more than 96% of the market, plus false publicity, so it is recommended to take a look at the relevant knowledge introduction. Have a bottom in your heart.

Find out what these things actually look like, and then ask for what you want to do with them.

In fact, it should be pointed out that the kind of request you mentioned, although unrealistic, has a tendency, that is, a desktop (tripod) telescope may be more suitable for your situation with high magnification requirements - however, this kind of telescope cannot be used by hand.

Take a look at the multiples aspect of the introduction.

<> is on a case-by-case basis. This involves three factors: 1. What is the observed environment, including light intensity and direction, contrast, atmospheric stability and transparency, etc.

2. The quality of the telescope itself, including specifications, categories, accuracy, etc. 3. The observer's vision condition after correction and the degree of proficiency in using the telescope.

What does the aperture of the telescope refer to:Aperture refers to the diameter of the telescope objective. The larger the aperture, the larger the observation field and brightness, which is conducive to observation in low light, but the larger the aperture, the larger the volume, and can generally be selected between 21-50mm according to the needs.

In recent years, there have also been some large-aperture telescopes with a diameter of 70mm, 80mm, and 100mm, which are very large and equipped with brackets.

To see a person's face clearly, you need to roughly distinguish between the two eyes.

It is equivalent to resolving two points that are 5 cm apart.

The observation distance is 1000m=100000cm

Therefore, the resolution angle of the telescope = atan(5 2 100000) = degrees = seconds, and the aperture of the telescope is roughly required: 280 mm.

The pupil diameter of the human being is 4-7mm, so the multiple = 54 7-54 5 = take 8-12 times) Because of factors such as air disturbance and lens quality, the multiple and caliber should increase year-on-year, so it is necessary to see the face at 1000 meters, the multiple shall not be less than 10 times, and the diameter shall not be less than 50mm

7-10 times.

The larger the magnification, the farther the distance, but at the same time, the hand tremor will also be amplified, which is easy to cause the effect of vertigo, it is recommended to buy 7-10 times is the best.

Precautions for the purchase of telescopes:

1. Optical quality and lightweight shape are often contradictory, and if you want both, you need to significantly increase your budget.

2. Each size and type of telescope has a specific environment suitable for its use in order to achieve perfect results, and no telescope is omnipotent.

3. The volume of the roof prism telescope is the smallest among the telescopes of the same specification, but the optical quality is often not as good as that of the porro prism telescope.

4. The price of the telescope depends on many external factors, such as cost, profit, market strategy, etc., and the multiple of the telescope has little to do with it.

5. The imaging effect of the telescope depends on many factors, and the magnification is only one of many factors, and it is not advisable to blindly pursue the magnification.

6. The possibility of military telescopes being fakes is extremely high, and regular military telescopes are basically black, and they are expensive.

7. Do not buy binoculars with a wide range of zoom, there are many problems such as small field of view, serious imaging distortion, and easy deviation of the optical axis.

8. You must know that you get what you pay for, and the actual effect of a telescope with the same specifications and parameters may be very different, and of course the hail will be thousands of miles apart.

9. Try not to buy a red film telescope, it is only suitable for high reflection environments such as ice and snow, and the imaging in the general environment is dim and the color cast is serious.

10. There has never been an infrared night vision telescope, but some specifications of telescopes such as 7x50 work very well in a low-light environment.