What are the main decisions about the quality of a telescope?

To put it simply, if you are a hobbyist, you can use a reflector. The quality of a good telescope depends mainly on the lens and barrel. The former should be polished meticulously, and the latter should be straight. I don't think it's worth much if you don't talk about the brand, but it's still as you ask.

So complicated? It is better to coat the garbage in blue film for the rest of the color.

The multiplier should not be less than 8 times, it is better, and the powerful one is 12 times.

So look at the size of the field of view at the same multiple, what is the field of view, that is, the diameter distance of the field of view 100 meters away, the larger the better, otherwise the field of vision will be dim, and there will be less things to see, that is, a wide angle.

Reflecting telescopes have many advantages, such as the absence of chromatic aberration, the ability to record information emitted by celestial objects in a wide range of visible light, and the fact that they are relatively easy to make compared to refracting telescopes. But since it also has inherent shortcomings:

For example, the larger the aperture, the smaller the field of view, and the objective lens needs to be coated regularly.

For the material of the mirror, it is only required that it has a small coefficient of expansion, less stress and is easy to grind. The surface of the polished mirror is usually coated with an aluminum film, which has a good reflection law for the infrared and ultraviolet regions, and is suitable for studying the spectral spectrum and luminosity of celestial objects in a wide range of wavelengths. In addition, reflecting telescopes generally have a shorter tube tube.

Large reflecting telescopes are mainly used for astrophysical research, especially for light splitting, photometry and direct photography of faint objects.

The performance of a reflecting telescope is highly dependent on the objective lens used. The spherical objective lens that is usually used is easy to process, but if the focal ratio of the telescope is relatively small, there will be a serious optical spherical aberration; In this case, the object will become blurred because the parallel rays cannot be precisely focused on one point. Therefore, the objective lens of large-aperture, high-intensity reflecting telescopes usually adopts an aspherical design, and the most common aspherical objective is a parabolic objective.

Due to the geometry of the parabola, the light rays parallel to the optical axis of the objective lens will be precisely focused on the focal point, thus greatly improving image quality. But even telescopes with parabolic objectives still have off-axis aberrations.

Hubble Space Telescope, but for your own use, consider Boguan and Xingtrang's! The quality and effect are good, and the ** is also cheap. Xiaoxiao has a shop outdoors, you can take a look.

You're talking about astronomical telescopes or monoculars, binoculars.

The effect of the telescope is definitely determined by the optical performance of the telescope itself.

Cost differences on optics. At present, the difference between optical parts is mainly in the eyepiece and prism, and the objective lens is basically not obvious (there are two reasons, one is that the objective lens has too much exposed area, which is easy to see if it is downgraded; The second is that most of the objective lens overtime itself is an excellent product, 98%).

First of all, the eyepiece, the eyepiece is generally divided into two levels, namely grade A and grade B, grade A is called **, grade B is called downgraded, and there are excellent grade and special grade on the **, but sometimes it is not distinguished, generally speaking, grade A and grade B have a 25% cost difference. In addition, eyepieces generally require three pieces of glass, that is, one monolithic and one glued part, in order to reduce costs, some manufacturers reduce it to two monoliths, which will reduce the cost by about 30%.

Speaking of prisms, prisms have four grades, namely A, B, C, and D, of which grade D cannot be used for export, and its cost is reduced by about 20% in turn. For foreign OEM products, it is generally required to be A-level, and sometimes B-class, but the telescopes on the Yiwu market are generally C-level and D-class.

The above only refers to the grade of optical glass, if ordinary glass or resin sheet is used, the cost is still greatly reduced.

In addition, the glass grade standards in different regions are also different, for example, the B-grade optical glass in Chengdu (Military Industry 208 Guangming Factory under the Ordnance Equipment Group) is more than the A-grade glass in some regions!

Materials, workmanship, caliber, and focal length.

Large aperture, high resolution, strong light collection power; The focal length is long and the multiples are high.