But out of curiosity, I felt a little touched after knowing the author's background. A good poem can often express some of the deepest and deepest feelings that human beings have.
This is this poem:
"Believe in the telescope.
Trust the telescope, not the eyes;
Believe in stairs, but never believe in steps;
Believe in wings, not birds.
Still believe in you, believe in you, only believe in you.
Believe in malice and don't believe in the wicked;
Believe in wine glasses, but never in shochu;
Trust the body, not the person.
Still believe in you, believe in you, only believe in you.
Trust many people, but no longer trust one person.
Trust the riverbed, but never the river;
Trust pants, not legs.
Still believe in you, believe in you, only believe in you.
Trust the window, not the door;
Trust your mother, but not for nine months;
Believe in fate, don't believe in golden dice,
Still believe in you, believe in you, only believe in you.
-Cé sar Valejo (Peru) "
The author experienced turmoil in Spain. In turbulent times, people can easily lose their faith in human nature. After all, few people have the opportunity to face real human nature. Very cruel.
After seeing it, you will also feel the emptiness, loss and fragility of a belief.
In his poem: "I believe in stairs, but I never believe in steps;"
Believe in wings, not birds.
Trust the river bed, but don't trust the river.
Believe in malice, don't believe in the wicked. "
That kind of "unbelief" is so lonely, hesitant and neurotic, like a frightened bird, and how fragile this belief is? Deceive yourself? Comfort yourself?
-But I still believe in you, only you.
This is the last belief and meaning of living in this world. It reveals the kind of hesitation, loss and despair in the tragic cherish, grab and refuge (feeling is, or a belief or doctrine) of the lover.
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The translation of the original text is not clear, the original text is not "you", but "yourself", that is, the author is talking to himself-so what I just understood, at least not the author's original intention = =
2. Telescopes in a broad sense include not only optical telescopes working in visible light, but also radio, infrared, ultraviolet, X-ray and even gamma-ray telescopes. Our discussion is limited to optical telescopes.
1609, Galileo made the first telescope, which has a history of nearly 400 years, during which he experienced a major leap. According to the type of objective lens, it can be divided into three types:
1, refractive telescope
The objective lens of a refractive telescope consists of a lens or lens group. The early objective lens was a monolithic structure, and the chromatic aberration and spherical aberration were serious, which made the observed celestial bodies stained. In order to reduce chromatic aberration, people try their best to increase the focal length of the objective lens. 1673, j Hevelius built a 46-meter-long telescope. The whole lens barrel is hung on a 30-meter-high mast, and many people need to pull it with ropes to rotate and lift it. Huygens just separated the objective lens from the eyepiece and hung it on a pole 100 feet high. Until the end of 19, people invented a compound achromatic objective composed of two pieces of glass with different refractive indexes, namely convex lens and concave lens, and then combined them into one, ending the length competition.
Refractive telescopes are divided into Galileo structure and Kepler structure. Galileo's structure is the oldest, and the eyepiece is a concave lens, which can directly form an upright image, but the field of view is small, which is generally 2-4 times that of civilian toys. However, most common telescopes are Kepler structures, and their eyepieces are usually convex lenses or lens groups. Because there are real images in their optical paths, you can install ranging or aiming crosshairs to measure the distance. However, the image formed by the simple Kepler structure is inverted, and an upright system needs to be added in the optical path to make it move forward. The common upright system is prism or roof prism, which not only plays an upright role, but also can make the light path fold back and shorten the length of the whole machine. (see photo)
2. reflecting telescope
This kind of mirror was first invented by Newton (see picture). Its objective lens is concave mirror, and there is no chromatic aberration. The spherical aberration can be eliminated by making the concave surface into a paraboloid of revolution. The concave surface is coated with a reflective film, usually aluminum. The mirror tube of reflective telescope is short, and it is easy to make it into a larger aperture, so almost all modern large astronomical telescopes are reflective structures.
In the structure of reflective telescope, in addition to the main objective lens, one or several small mirrors are installed to change the direction of light and facilitate the installation of eyepiece. Because the incident light of reflective telescope is only reflected on the surface of objective lens, the intrinsic quality of optical glass is lower than that of refractive mirror. 1990, the United States built the largest Keck telescope in Hawaii at that time. The mirror adopts some unprecedented new technologies: 1, and the main objective lens is composed of 36 hexagonal thin lenses with a thickness of only 10 cm. 2. A computer controls the straight support point on the back to compensate the deformation caused by gravity. 3. Atmospheric disturbance can be compensated by changing the curvature of the mirror. The adoption of these new technologies makes it no longer urgent for human beings to launch space telescopes.
3. reflecting telescope.
The objective lens of a catadioptric reflecting telescope consists of a refracting mirror and a reflecting mirror. The primary mirror is a spherical mirror, and the secondary mirror is a lens to correct the difference between the primary mirror and the secondary mirror. This kind of telescope has a large field of view and strong light, which is suitable for observing meteors and comets, and is also suitable for surveying the sky to find new celestial bodies. According to the shape of the secondary mirror, catadioptric mirror can be divided into Schmidt structure and Maksutov structure, the former has large field of view and small aberration; The latter is easy to manufacture.
For more information, see:
3. About the telescope Beijing Xinghe Telescope will answer your questions:
Hello, binoculars are suitable for sightseeing, watching football matches or concerts. At present, Guanbo is a better brand of binoculars in China, especially binoculars, which have many series and models and have a good reputation. The binocular ratio is 7- 10. If the ratio is too high, hand jitter will easily affect the observation effect. The caliber is about 50, which is relatively good, with large caliber, large observation field and high comfort.
Hunter 7*50 is a better choice, the price is around 400 yuan, and the cost performance is very high, which belongs to the mid-range binoculars. Better waterproof and fog-proof, and higher price, such as crossing 8X42,10x42 (more than 600 yuan); Be optimistic about 8X42 (around 900 yuan). These models are waterproof and fog-proof, with sharp imaging, high definition, good coating process and high quality.
The following are some shopping precautions, please refer to:
The selection of two parameters of binoculars is very important. One is a multiple of the aperture, such as 7*50 or 8*42.
One: multiple: the number before the asterisk (*) is a multiple,
Ordinary binoculars, the multiple is 7- 10 times, generally not more than 12 times. If the multiple is high, it will shake when held, which will affect the observation effect.
2: Caliber: The amperage after the asterisk (*) is the caliber.
Large-caliber observation has large field of vision, high brightness and high comfort. If you want to observe a large area, it is recommended to choose a large caliber, but it is relatively large.
Three: the ratio of caliber to multiple:
The ratio of multiple 7 caliber 50 is relatively high observation comfort, but if you like high-magnification observation, you can choose 10 times.
You can go to the knowledge area of Galaxy Telescope and search for "Galaxy Telescope" in Baidu, which contains a lot of knowledge about telescope purchase, maintenance and use. At present, a variety of telescopes are on sale, and there are gifts!
As for the telescope, it seems to be the so-called "autofocus telescope".
Most "autofocus telescopes" are actually fixed-focus telescopes, that is, when designing the optical system, the focal length range of the object field is set in advance, such as 10 m to 2000 m, so that the scenery within this distance can be watched normally.
Theoretically, the closer the nearest focus range is, the farther the farthest range is, such as 0~ infinity. Generally speaking, the greater the nearest clear distance and depth of field, the better. But it is actually very difficult, because the smaller the focal length from the objective lens to the scene, the longer the focal length from the objective lens to the focal plane of the eyepiece, and the size of the whole system will be greatly increased. In view of the above problems, we can solve them by increasing the focusing range of the eyepiece.
Therefore, sometimes a telescope with large depth of field is called an autofocus telescope.