Knowledge of astronomical telescopes

Astronomical telescope is an important tool for observing celestial bodies, so how much do you know about astronomical telescope? The following is my knowledge about astronomical telescope, I hope you like it!

Structure of astronomical telescope

1, the main mirror consists of objective lens (front lens group), focusing system and eyepiece (rear lens group). The lens barrel will be marked with the focal length of the main mirror, which is indicated by F, F600 means that the focal length of the main mirror is 600 mm, and the main mirror is marked with the aperture, and 80 mm means that the aperture is 80 mm. Please note that the aperture is the first criterion to determine the performance of the telescope, and the larger the aperture, the better. The eyepiece is an individual and determines the magnification. There will be an f value on the eyepiece, which is the focal length of the eyepiece. Divide the f value of the primary mirror by the f value of the currently used eyepiece, which is the current magnification. Remember, magnification is the standard. The limit magnification of a telescope with a diameter of 6 cm is about 120 times, and the maximum magnification of 8 cm is about 160 times. If it exceeds this range, the object cannot be seen clearly. In addition, the field of vision of astronomical telescope will not be as wide as that of binoculars. If you want to see a wider area, you can choose an eyepiece with a large f value (such as 20mm, 25mm, 40mm), otherwise the viewing range will be reduced (such as 8mm, 12mm, 4mm). The eyepiece field of view of a general household astronomical telescope is 1 degree (two full moons in diameter, which means that your field of view can hold two full moons). Focusing system is a device to adjust the definition.

The star finder is a very important accessory, especially for beginners, because its function is to find the target. So why can it find the target? This is relative. As we said above, the general telescope field of view is 1 degree, while the star finder can reach 6- 10 degree, so the star finder with large field of view is easier to find the target than the main mirror. From the eyepiece of the viewfinder, we can see that there is a crosshair in the field of vision. This is the positioning device, and how to use it will be discussed below. Another device of the viewfinder is that it has three screws to adjust the direction of the viewfinder, which will be mentioned below.

3. The manual control device greatly facilitates us to know and find the stars, input the local latitude and longitude, and make the telescope point to the north and horizontal. Then find one, two or more stars, and you can find stars, planets, nebulae, clusters, constellations and so on. According to the built-in star name, you can move with the star when you find it.

Operation flow of astronomical telescope

If the telescope is equipped with a declination instrument, the balance between the declination axis and declination axis of the telescope must be adjusted. (The specific steps are omitted. )

1. Adjust the optical axes of the main mirror and the star finder to be parallel.

After installing the telescope, we first choose a relatively large building target, such as chimney, outdoor unit of air conditioner, etc. Don't worry about the star seeker. First, choose the eyepiece with the largest F value for the telescope and install it on the main mirror (generally 20mm or 8mm), and use the main mirror to slowly find the object you want to see. Take a sign on the outdoor unit of an air conditioner as an example. We choose large objects to make the main mirror easy to find. Large objects are easy to find. We adjust the focal length system to make the image clear and keep the image in the center of the main mirror's field of view. Once found, lock all tripods. Pay attention, carefully observe the image in the main mirror, draw a cross average of the field of view of the main mirror in your mind, and see which part of the image the center point is.

Step 2 Adjust the viewfinder

The main mirror has repaired the image. Let's adjust the viewfinder. Turn the three screws on the viewfinder slowly.

Adjust slowly, and adjust the image just in the center of the main mirror to the center of the viewfinder crosshair as much as possible. Be patient, this may be the most anxious time. It should be noted here that sometimes we do adjust the image to the center, but observing the three screws, it is possible that one of them is not butted against the viewfinder, which means that the adjustment is unsuccessful, just by accident, so we must observe that the three screws should butt against the lens barrel, even if it is only slightly touched, because moving the mirror will not affect the viewfinder in the future. When the image is adjusted to the center, the adjustment of the optical axis is completed.

3. The purpose of the above two links is to make the optical axes of the two lens barrels parallel, instead of observing an individual. Must understand.

Well, when the optical axes of the two mirrors are parallel, we can observe all the objects. The specific operation is as follows:

Loosen the tripod just locked, and slowly move to the general direction of the observed object, gently, otherwise the viewfinder may shake, and the previous work will be in vain. After moving to the approximate position, first observe and aim through the viewfinder, and put the observed object in the middle of the viewfinder cross (turn the tripod, not the viewfinder). After reaching the center, observe the main mirror, and you will find that the observed object honestly appears in the field of vision of the main mirror, and it becomes clear to adjust the focal length. This is because the optical axes are parallel. If you can't see it, it still means that the optical axis is not adjusted well, or you accidentally moved the viewfinder when moving, so you can only adjust it patiently.

Selection of astronomical telescope

1, telescope is a price, so don't covet the cheap goods and products of small workshop manufacturers. Some well-known telescope brands in China (such as Xinglin, MIDE, Guanbo, Ai Mufu, Sirius, Jinghua and Xingtong). ) the quality and reputation are good, there are formal sales outlets, and you can choose your own telescopes on the spot. For telescopes below 100mm, domestic brands have quite good cost performance.

2, according to the individual's economic ability, try to choose a large-caliber telescope;

For beginners, ordinary stargazing can choose 7X50 binoculars, which are easy to carry. For better conditions, it is recommended to choose 60 mm, 70 mm and 80 mm refractors:

First of all, it is easy to carry, use and maintain, and can be often taken out for observation (100mm is relatively overweight and inconvenient to carry; How much depends on the number of observations rather than the diameter of the telescope);

Secondly, even in cities with severe light damage, you can see sunspots, the moon and bright celestial bodies such as Jupiter and Saturn.

In addition, the price is low. If you buy a bigger and better telescope in the future, you can upgrade it as a star guide and make full use of it.

There are many brands of astronomical telescopes, each with its own advantages and disadvantages. But these are all things that we can bear or not affect the observation of introductory learning. Remember, there is no perfect mirror. Choosing the one that suits you is the most important. It took you a year to choose what kind of mirror to buy, so you have one year less observation and study time than others, and your use and understanding of the mirror itself is also backward. I mean, no matter how much you listen to others, you can't compare with the benefits of holding a mirror yourself.

Matters needing attention in using astronomical telescope

1, never look at the sun directly with a telescope, but look at the sun through projection or special filtering measures, otherwise it will burn the retina and cause certain damage to the primary mirror.

Don't use binoculars as toys. Telescopes are precise optical instruments, so be careful to use and maintain them.

Don't think that you can see everything with a telescope. You can really see celestial bodies and details on celestial bodies through telescopes, but the better the viewing effect, the higher the price. There is no perfect telescope, so it is most important to choose the one that suits you.

4. Every telescope has its proper magnification. Exceeding this multiple will not enhance the resolution, but will make the object very dark and difficult to see. For a telescope with a diameter of 60 mm to 80 mm, the appropriate magnification should be less than 100 times, and almost nothing can be seen when magnified 200 times.

5. If you can't identify more than five constellations in the night sky, don't use a telescope in a hurry, because you can't find observable stars, you can only look at the moon;