2023-05-12
Classification of telescopes
Countries around the world are divided into two completely different concepts in terms of telescope performance, magnification, aperture, exit pupil diameter and distance, image rotation, focusing form, process structure, optical coating, imaging quality, appearance and additional functions. The schools are represented by the Eastern socialist countries headed by the former Soviet Union and the Western capitalist countries headed by the United States and the former West Germany.
Theoretical differences in telescopes and the choice of aperture, magnification, and image rotation
The effectiveness of a telescope is determined by both magnification and aperture. To a certain extent, increasing the magnification of the telescope or increasing its aperture or using the above two measures at the same time can achieve similar observation effects. There are two telescope theories, one pays more attention to magnification and tends to adopt an exit pupil diameter close to 3mm; the other is the classic Chase school, which emphasizes aperture and tends to adopt an exit pupil diameter close to 7mm. The views of the Russians have always been practical, which is a typical multiplier school. It can be seen from their product specifications that the exit pupils of Russian-made telescopes rarely exceed 5mm except for marine and export-oriented telescopes. In the west, only small-aperture portable telescopes can get close to 2.5mm. In order to achieve the same observation efficiency, the Russians are obviously more inclined to increase the magnification of the telescope. the
Russia's emphasis on magnification is also related to its industrial base and telescope structure. Compared with Western technology, Russia is weak, especially because of artificial reasons, the quality of assembly is generally poor. The difficulty and cost of processing large-diameter lens groups is much higher than that of processing small-diameter short focal length lenses, especially in the bonding of objective lenses. Coupled with the reasons of traditional guiding ideology, the pragmatic Russians naturally chose to increase the magnification. At the same time, Porro prisms are easy to process, low in cost, and have good imaging effects. Therefore, they are far more popular with the Russians than the expensive, complicated and unreliable roof prisms. Therefore, except for the varieties specially exported to the West, Russian telescopes are basically Porro prisms. And if the aperture of the objective lens is too large, the telescope will be too big and heavy. Therefore, due to the constraints of the telescope structure, the Russians also tend to increase the magnification in order to manufacture relatively lightweight telescopes. Among the telescopes of the same caliber in the east and west, the telescopes of the Russians can be called "high power telescopes".
However, the weight of the magnification cannot be increased infinitely, and the magnification is also at the expense of certain observation performance. For example: dark light observation ability, brightness, clarity, comfort, field of view, exit pupil distance, observation ability under shaking conditions, etc. Therefore, the magnification of the telescope is not as big as possible, depending on the purpose. The visibility factor of a handheld telescope is generally not greater than 500. The most versatile and portable telescope is the 8x30 with an index between 210-260 followed by the 7x35. High magnification lenses are clear, but poor portability. So the most versatile telescope is the one with the perfect balance of viewing power and portability.
The West, represented by the United States and Germany, advocates large-aperture telescopes. Among the full-aperture telescopes, the 8x telescope of Chase Company can achieve a diameter of 56mm, which breaks through the regulation that the diameter of a hand-held telescope should not exceed 50mm, and is close to the transitional diameter of 60mm. In the west, the magnification of hand-held telescopes rarely exceeds 10 times and generally adopts 42, 50mm and other apertures.
Attitudes to Pocket Telescopes
Russian industry largely serves the military. Because roof prism binoculars with a caliber of less than 30mm have no military value, pocket binoculars are simply toys in their eyes. It is difficult to find such things in their product catalogs. If they are found in time, they are only exchange products sold to the West. .
The attitude of Westerners is very different. To some extent, it can be considered that they attach great importance to this supplement of "the bird is not seen with a gun, and the bird is not with a gun". In order to obtain better observation efficiency, Westerners uncharacteristically became the school of caliber. Pocket telescopes generally appear as day-use telescopes. Because this kind of gadget with stylish appearance, small size, light weight, easy to carry and collect can well meet the needs of consumers to carry it around and take a quick glance.
The material and shape of the telescope
Russia tends to use metal materials in terms of mirror body materials. In fact, both plastic and metal can withstand the test of harsh weather and harsh use environment. Strictly speaking, suitable plastics have the strength equivalent to metal, and even have certain advantages in terms of weight, corrosion resistance and cost. Therefore, the Russian telescope first chooses aluminum alloy as the mirror body material. The appearance of the Russian telescope has not changed much for decades. It has a traditional appearance and is loved by some people. This is also related to the concept of the Russians, who value mature technology and production costs. Western industrial technology has a strong foundation, composite materials and computer-aided processing technology are developed, and processing precision is high. Therefore, in addition to military, maritime, astronomical and other professional telescopes that require high imaging quality, in order to balance volume and weight, roof prism systems and rubber-coated engineering plastic mirror bodies are often used. These measures make it possible to manufacture telescopes with larger apertures that are relatively light and compact.
However, the appearance of western telescopes has changed a lot, and new varieties of civilian telescopes are constantly being launched. Decades of shadows are hard to see from today's Western telescopes. The West attaches great importance to consumer psychology. It is believed that only by continuously launching new varieties can consumers' desire to buy be continuously stimulated, and consumers are more willing to pay more for novelty products.
Imaging characteristics and coating technology
The images of Russian telescopes are generally yellowish, with a wide viewing angle but rapid and obvious edge image quality degradation, visible chromatic aberration and distortion, severe ghosting and glare, poor brightness and obvious individual differences. Even so, it is still a telescope with excellent imaging, and the effect far exceeds that of many domestic telescopes. For observation and measurement purposes, it is completely sufficient. The coating of Russian telescopes is relatively simple and conservative. Generally, the single-layer anti-reflection coating is based on 555nm yellow-green light as the center wavelength. Exactly the same, the image is generally yellowish. The ghost image of the Russian telescope has a lot to do with the insufficient anti-reflection ability of its coating, which is caused by the reflection of the object image back and forth between different optical interfaces. In recent years, in order to improve the yellowish phenomenon, the center wavelength of the lens coating has been adjusted to the short-wave green-blue or blue-light segment, so the color of the lens has changed to purple-red or brown-yellow, and the decorative effect of the lens has been increased. There are not many varieties of Russian telescopes coated with multi-layer coatings, which are green bimodal coatings. There are very few varieties of Russian-made telescopes coated with decorative films. But in recent years, in order to meet the needs of the market, 8x30 coated with ruby film is also produced.
Western high-end telescopes can be said to strive for excellence in imaging. The colors are vivid and the field of view is not necessarily large. Advanced optical processing and coating technology. Western telescopes pay more attention to coatings. General telescopes have single-layer coatings on the entire surface. The better varieties are green bimodal coatings or full-surface bimodal coatings. High-grade varieties are coated with multi-channel multi-layer coating or full-surface multi-channel film, and the reflection is rarely faint dark red. Excellent western telescopes have a light transmission power of more than 95%. The excellent image quality and bright field of vision of western telescopes are largely due to their excellent coating technology.
other
The design of Russian telescopes is relatively old, so some functions that are more important now are often not considered. For example: the exit pupil of Russian-made telescopes is generally relatively short, which is not conducive to wearing glasses, using filters or observing with a gas mask. The focusing method is relatively simple, and there are few varieties with waterproof and shockproof functions.
Western telescopes pay more attention to ergonomics and additional functions, and do a better job in terms of the exit pupil distance, focusing method, shockproof, waterproof, antifog, and luminous reticle of the telescope. At the same time, it also pays great attention to the shape and technology of the product. Make the telescope adapt to more users with different needs and various use environments
Summarize
Western telescopes have come to the forefront of the world because of their strong financial resources and strong industrial foundation. The Russian telescope comes next, but it is an excellent telescope for its traditional style, practical function, and economical price. Compared with many domestic telescopes, it still has an overwhelming advantage.
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