Ask about how to use the dome telescope. The school has a very large telescope with a dome, but I don’t know how to use it. Could you please explain some basic steps in detail?

Magnification Common telescopes) are represented by: magnification is 50 mm. Boguan ED astronomical telescope

How to express the specifications of the continuous zoom telescope: The continuous zoom telescope is expressed by "lowest magnification - maximum magnification x objective lens diameter (diameter mm)", such as 8-25x25 represents the The minimum magnification of this telescope is 8 times, the maximum magnification is 25 times, it can be continuously changed between 8 times and 25 times, and the aperture is 25 mm. The expression method of fixed variable magnification telescope: low magnification/high magnification (/higher magnification) 30*80 refers to a telescope with a magnification of 15 times and a fixed zoom of 30 times, and an aperture of 80 mm. How to express a waterproof telescope: Generally, WP (Water proof) is added after the telescope model. For example, 8X30WP refers to a waterproof telescope with a magnification of 8 times and an objective lens diameter of 30 mm. How to express a wide-angle telescope: Generally, WA (Wide Angle) is added after the telescope model. For example, 7X35WA refers to a wide-angle telescope with a magnification of 7 times and an objective lens diameter of 35 mm. Some dealers use the product of the two numbers before and after as the magnification of the telescope. It is unethical to deceive consumers, and some dealers arbitrarily expand two numbers to deceive consumers. I once saw a 10x25 DCF telescope, and the marked specifications were actually 990x99990. Oh my god! What is the concept of a 990x telescope with a diameter of 99990mm?

What does the magnification of a telescope mean?

The magnification of a telescope: The magnification of a telescope refers to the ability of the telescope to bring objects closer, such as using a 7x telescope to observe objects. , the effect observed on an object 700 meters away is similar to the effect observed on an object 100 meters away with the naked eye (of course, the effect is worse due to the influence of the environment). Many people always think that the higher the magnification, the better. Some dealers and manufacturers also use false high magnification to attract and deceive consumers. Some telescopes on the market are actually marked as 990 times! In fact, the reasonable magnification of a telescope is related to the aperture of the telescope and the observation method: if the aperture is large, the magnification can be appropriately higher, and the one with a bracket can be higher than the hand-held one. The greater the magnification, the worse the stability, the smaller and darker the observation field, the greater the jitter it brings, and the greater the impact of breathing airflow and air fluctuations. The most suitable binoculars for handheld observation are between 7 and 10 times, and it is best not to exceed 12 times. If the magnification of the telescope exceeds 12 times, then hand-held observation will be very inconvenient. Most military telescopes in various countries around the world are mainly 6-10 times. For example, my country's military telescopes are mainly 7 times and 8 times. This is because clear and stable imaging is very important.

What is the field of view of a telescope

Field of view refers to the size of the range observed within a certain distance. The larger the field of view, the wider and more comfortable the observation range will be. The field of view is generally expressed by the view horizon (observable width) in kilometers and the angle of view. There are three common expression methods: one is directly Use angle, such as angle of view: 9°; second, the visual range at kilometers, such as Field of view: 158m/1000m; third, feet at thousand yards, which is actually similar to the second one, such as Field of vies: 288ft/1000y. Generally speaking, the larger the aperture and the lower the magnification, the larger the field of view, but the design of the eyepiece group is also critical.

What is the exit pupil diameter

The exit pupil diameter is the size of the spot formed on the eyepiece after the image passes through the telescope. The exit pupil diameter can be obtained by using the following formula: Objective lens port lens/magnification =Exit pupil diameter. It can be seen that the larger the objective lens and the lower the magnification, the larger the exit pupil diameter will be. Theoretically, the larger the exit pupil diameter, the brighter the observed scene, which is conducive to observation under dim light. Therefore, when purchasing a telescope, you should try to choose one with a larger exit pupil diameter. So, is bigger the better? No, because we usually use telescopes during the day, when the pupil of the human eye is very small, only about 2-3 mm. At this time, if you use a telescope with a large exit pupil diameter, such as more than 4 mm, most of the useful light will not It is not absorbed by the human eye and is instead wasted. The pupil of the human eye can reach about 7 mm only at dusk or darkness. Therefore, under normal circumstances, it is enough to choose an exit pupil with a diameter of no less than 3 mm. Therefore, the exit pupil diameter is also called the dusk factor.

What is coating? What is the function of coating

If you observe carefully, you will find that there are different colors outside the objective lens of the telescope, such as red, blue, green, yellow, purple, etc. , this is what is commonly called coating. What is the function of lens coating? The function of the lens coating is to prevent the mist-like white phenomenon caused by the diffuse light reflected on the lens, to nourish the reflection, increase the light transmittance, increase the contrast and sharpness of the color, and improve the observation effect. Generally, the more, deeper and thicker the coating layers, the better the viewing effect and the higher the brightness. The color of the coating needs to be determined according to the optical material and design requirements. The lighter the coating and the smaller the reflection, the better. Blue film and red film are the most commonly used. Blue film is a traditional coating, and red film is from the first half of the last century. appeared. Many people think that red coating is better than blue coating. Now there are many highly reflective and shiny red coating telescopes on the market. Some dealers call this coating "infrared", "sub-infrared", "ruby coating" and so on. Finally They will tell you that this is an all-weather infrared night vision telescope that can observe at night. Please don’t be fooled. The real infrared night vision device uses photoelectric tube imaging, which is completely different from the structure and principle of a telescope. It cannot be used during the day and requires a power source to observe. In fact, when light penetrates glass, it will inevitably cause some reflections and reduce the brightness. After being coated with red film, the brightness will decrease even more due to severe reflection. This type of telescope is usually used to reduce the brightness when the sun is shining brightly on the snow. , when used under normal circumstances, the blue film is relatively good (many famous brand cameras and camera lenses are coated with blue film, this is the reason).

What do DCF, UCF and PCF mean?

DCF, UCF, and PCF are people’s customary names for telescope models. DCF refers to a straight telescope using a Biehan prism. UCF refers to a small telescope using a Paul prism, which is often called Little Paul. , using an inverted prism structure, PCF refers to a large telescope using a Paul prism, which is often called a large Paul portable astronomical telescope

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Edit this section on the operation of astronomical telescopes

There are generally two lens tubes on astronomical telescopes. The larger one is the main mirror, which is used for observing targets; the smaller one is called the telescope. A starscope is used to find targets, also called a sighting scope. Every time we take the telescope out of the box and install it or move it significantly, we have to readjust the parallelism of the optical axes of the two mirrors to create a convenient environment for observation. First, let’s talk about the simple operation method: Astronomical telescope structure

Structure

1. The main mirror consists of the objective lens (the front lens group), the focusing system and the eyepiece (the end Composed of lens group), the focal length of the main mirror will be marked on the lens barrel, represented by F. F600 means that the focal length of the main mirror is 600 mm. The diameter of the main mirror will be marked on the main mirror. 80mm means the diameter is 80 mm. Please note that, Aperture is the first criterion that determines the performance of a telescope. The larger the aperture, the better. The eyepiece is a separate entity, an item that 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 main lens by the F value of the currently used eyepiece, which is the current magnification. Remember , the magnification is standard. The ultimate magnification of a 6 cm telescope is about 120 times, and the maximum magnification of an 8 cm telescope is about 160 times. If you exceed this range, you will not be able to see objects clearly, so the telescopes on the market that magnify hundreds of times are all Parallel imports cannot be enlarged to that magnification, so don’t believe it. In addition, the field of view of an astronomical telescope will not be as wide as that of binoculars. If you want to see a wider area, you can choose eyepieces with a large F value (such as 20mm, 25mm, 40mm). Otherwise, the range you can see will be narrowed ( Such as 8mm, 12mm, 4mm). The eyepiece field of view of a typical home astronomical telescope is 1 degree (the diameter of two full moons, which means you can fit two full moons into your field of view). The focusing system is a device that adjusts sharpness. 2. The finderscope is an important accessory, especially for novices, because its function is to find targets. So why is it able to find targets? This is relative. As we said above, the field of view of a general telescope is 1 degree, while a finderscope can reach 6-10 degrees, so a finderscope with a large field of view is better than a main finder. A mirror makes it easier to find targets. When we look through the eyepiece of the finderscope, we can see a crosshair in the field of view. This is the positioning device. How to use it will be discussed below. Another equipment of the finderscope is that it has three screws, which are used to adjust the direction of the finderscope, which will be discussed below.

Operation process

1. Adjust the optical axes of the main mirror and the finder mirror to be parallel. After installing the telescope, first we select a relatively large building target, such as a chimney, air conditioner, etc. Outdoor unit, etc. Ignore the finderscope, first choose the eyepiece with the largest F value equipped with the telescope and install it on the main mirror (usually 20mm or 8mm). Use the main mirror to slowly find the object you are looking at. Here is an example of a sign on an air conditioner outdoor unit. , we choose large objects so that they can be easily found by the primary mirror. Large objects are easy to find. We adjust the focus system to make the scene clearer and keep the image in the center of the main mirror. After finding it, lock the tripod.

Pay attention, carefully observe the effect in the primary mirror, draw a cross average of the primary mirror's field of view in your mind, and see what part of the image the center point is. 2. Adjust the finder mirror. The main mirror has set the image. Now let’s adjust the finder mirror. Turn the three screws on the finderscope and adjust slowly to bring the image just in the center of the main mirror to the center of the finderscope's crosshairs as much as possible. You must be patient. This may be the most impatient time. It should be noted here that sometimes we do adjust the influence to the center, but if we observe the three screws, it is possible that one of them is not pressing on the finderscope, which means that the adjustment was unsuccessful and it was just a coincidence, so be sure to observe the three screws. It should be pushed against the lens barrel, even if it only touches a little, so that moving the mirror in the future will not affect the finderscope. 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 tubes parallel, not to observe an object, so you must understand it clearly. 4. Okay, now that the optical axes of the two mirrors are parallel, we can observe all objects. The specific operations are as follows: Loosen the tripod that was locked just now, and slowly move it to the general direction of the object to be observed. Be gentle, otherwise the finderscope may shake, and the previous work will be in vain. After moving to the approximate position, first observe and aim through the finderscope, and place the object to be observed in the middle of the cross of the finderscope (it is a rotating tripod, not the finderscope). After reaching the center, observe the main mirror. You will find that the object being observed appears honestly in the field of view of the primary mirror, and it will become clearer by adjusting the focus. This is because the optical axes are parallel. If you can't see it, it means that the optical axis is not adjusted properly, or the finderscope was accidentally moved when moving, so you can only adjust it patiently.

Basic knowledge for editing this paragraph

Optical type

1. Refraction type: easy to use, large field of view, bright star image, but there is chromatic aberration, which will reduce resolution, easier to use and maintain. 2. Reflective type: no chromatic aberration, but large coma and astigmatism, which deteriorates the image quality at the edge of the field of view; commonly used are Newtonian mirrors, which have a simple optical system and the largest diameter of the mirrors available at the same price. The strongest light gathering power. 3. Catadioptric type: combines the advantages of refractors and reflectors: large field of view, good image quality, short lens barrel, and easy to carry. There are two types: Schmidt-Cassegrain and Maksutov-Cassegrain.

Basic optical performance parameters

1. Aperture: the effective diameter of the objective lens, which theoretically determines the performance of the telescope. The larger the aperture, the stronger the light-gathering ability, the higher the resolution, and the greater the available magnification; 2. Light-gathering power: light-gathering ability, the ratio of the amount of light received by the telescope to the amount of light received by the naked eye. The human pupil is approximately 7mm in diameter when fully open. The light-gathering power of a 70mm telescope is 70/7=100 times. 3. Resolution: The ability of a telescope to resolve image details. The resolution is mainly related to the aperture; 4. Magnification: the ratio of the focal length of the objective lens to the focal length of the eyepiece, such as the Pioneer 60/700 astronomical telescope, using H10mm eyepiece, magnification = objective lens focal length 700mm / eyepiece focal length 10mm = 70 times; the magnification factor changes. Bigger, the bigger the image you see. The bigger the magnification, the better. The maximum usable magnification is generally not greater than 1.5 times the diameter in millimeters. After exceeding the maximum effective magnification, the image will become larger but the clarity will not increase. 5. Focal ratio: The ratio of the focal length of the objective lens to its aperture, which is equivalent to the aperture on the camera lens. If the aperture remains unchanged, the longer the focal length of the objective lens, the larger the focal ratio, and the higher the magnification it is easier to obtain; the shorter the focal length of the objective lens, the smaller the focal ratio, and it is not easy to obtain a higher magnification, but the image will be brighter and the field of view will be larger. * Short focal length lens (small focal ratio, focal ratio <= 6): suitable for observing nebulae and finding comets; * Long focal length lens (large focal length, focal ratio > 15): suitable for observing the moon and planets; * Medium focal length lens (medium Focal ratio, 6

Bracket mechanism

1. Horizontal type: simple structure and use, low adjustment accuracy, unable to track celestial bodies, suitable for beginners; 2. Equatorial ceremony: the equatorial mount is used for observation It counteracts the rotation of the earth and tracks the movement of celestial bodies; its structure and use are complex, and its adjustment accuracy is high; equatorial mounts are available in manual and electric versions. Manual tracking equatorial mounts are suitable for specialized astronomical observations, while high-end electric tracking equatorial mounts are mostly used for specialized astronomical tracking photography and observation research; After beginners are familiar with the horizontal mount, they can choose a manual equatorial mount. The adjustment may be complicated for the first time, but observing the starry sky will be much easier after getting familiar with it. Amateurs often use electric tracking equatorial mounts (conductance) when learning astrophotography. But the price is more expensive.

Identification of optical quality

During the day, you can use a telescope to observe distant buildings. Move the outline of the building to 1/4 of the field of view. If the outline is orange or blue-purple, It is particularly obvious, or the contour line is extremely curved, and the optical quality is very poor; then look at the leaves in the distance. Generally, a 60mm diameter telescope can clearly see the leaf ribs of leaves 40 meters away. If you cannot see clearly, it means that the optical quality is very poor. (Boguan Pioneer 60/700 can clearly see the tendrils of sycamore leaves 60 meters away); when observing stars at night, if you see stars with obvious colors, or stars at the edge of the field of vision dragging tails, their lengths reach the size of stars 2 times, indicating that the optical quality is very poor and not suitable for astronomical observation; *Choose the 31.7mm (1.25 inch) large eyepiece interface to obtain better optical quality.

Edit this paragraph to purchase

1. You get what you pay for in telescopes. You must not buy products from street stalls or small workshops for cheap. Some well-known telescope brands in China (such as Boguan, Aimufu, Sirius, Jinghua, and foreign brands such as Cetel, etc.) have good quality and reputation. They have regular sales points and you can choose them on site. For telescopes below 100mm, , domestic brands of telescopes are quite cost-effective. 2. According to personal financial ability, try to choose a telescope with a large diameter; for beginners, 7X50 binoculars can be used for general stargazing, which is easy to carry. It is recommended to choose 60mm, 70mm, and 80mm caliber refractors if the conditions are better: * It is easy to carry, use and maintain, and can be taken out for observation frequently (above 100mm is relatively heavy and difficult to carry; the amount of things you can see depends on the observation times rather than the diameter of the telescope); * Even in cities with severe light pollution, you can view sunspots, the moon, Jupiter, Saturn and other bright celestial objects; * Low price, you can upgrade when you buy a bigger and better telescope in the future Make full use of it as a guide scope;

Notes on use when editing this paragraph

1. Never use a telescope to view the sun directly. Viewing the sun must use projection method or special light filtering measures 2. Don’t treat telescopes as toys. Telescopes are precision optical instruments and should be used and maintained carefully. 3. Don’t think that you can see everything with a telescope. Through a telescope, you can indeed see celestial objects and details on celestial bodies that cannot be distinguished by the naked eye. But the better the viewing effect, the higher the price. There is no perfect telescope, and it is most important to choose the one that suits you; 4. Every telescope has its appropriate magnification. Exceeding this multiple will not enhance the resolution, but will make the object very dark and difficult to see clearly. For a telescope with a diameter of 60 to 80, the appropriate magnification should be less than 100 times. With a magnification of 200 times, almost nothing can be seen. 5. If you cannot identify more than five constellations in the night sky, do not rush to use a telescope, because you cannot find observable stars, so you can only look at the moon; 6. Astronomical telescopes can usually also be used to view landscapes or animals and plants, which can be easily Get higher magnification than binoculars. However, the magnification ratio should be below 100 times, and 20-50 times is most suitable.

Understood