Tell us a little bit about telescopes

The following indicators, I personally feel, the more important the first:

1. The caliber of the objective lens: the bigger the brighter, the bigger the more details you can see, of course, it will be bulky if it is too big.

2. Exit pupil aperture: 4mm-7mm. It has the greatest impact on brightness. (The brightness coefficient is its square, the pupil opening range of the human eye is mostly 4-7mm, the field of view is too dark if it is less than 3mm, and it is not necessary to waste light if it is greater than 7mm).

3. Exit pupil distance: about equal to the focal length of the eyepiece, it should be greater than 10mm, if it is too small, the eyes must be close to the eyepiece, so that there will be a "ghost" when wearing glasses

4. To be a famous brand factory, the optical quality of the lens is basically guaranteed, and the lens anti-reflection film should be green, green is better than blue, better than red.

5. Multiples: Generally, of course, I hope that the larger ones are enjoyable, but the large multiples should be matched with large caliber and long size, so they should be appropriate.

6. If the prism is BK4, the optics of BK7 are worse.

7. Apparent perspective: Feel how many angles there are in the scene, generally greater than 60 degrees of wide angle is better.

8. The eyepiece should be large, and the diameter should not be less than 10mm, so that it looks comfortable.

Enjoyable at home (bracket fixed): 20x80, 25*100

It depends. In the case of a Newtonian telescope, then the objective lens is equivalent to a concave mirror; In the case of a Keplerian telescope, then the objective lens is equivalent to a convex lens; In the case of a Galilean telescope, then the objective lens is equivalent to a convex lens. A telescope is an optical instrument that uses lenses or mirrors and other optical devices to observe distant objects.

It uses the refraction of light through the lens or the reflection of the light through the concave mirror to make it enter the small hole and converge for imaging, and then pass through a magnifying eyepiece to be seen, also known as "clairvoyance".

Telescope role:The first purpose of a telescope is to magnify the opening angles of distant objects, so that the human eye can see details with smaller angular distances. The second function of the telescope is to feed the beam of light collected by the objective lens that is much thicker than the diameter of the pupil (up to 8 mm) into the human eye, allowing the observer to see faint objects that were previously invisible.

In 1608, Hans Lieberch, a Dutch optician, stumbled upon the idea that he could see in the distance with two lenses, and he built the first telescope in human history. In 1609, Galileo Galilei, a native of Florence, Italy, invented the 40x double-mirror telescope, which was the first practical telescope to be put into scientific applications.

The main parameters of the telescope are:

1. Magnification.

Generally, the ratio of the angle of view of the eyepiece to the angle of incidence of the objective lens is used as the magnification of the telescope, and the ratio of the focal length of the objective lens to the focal length of the eyepiece is usually used to calculate the magnification of the angle of view of the telescope. For example, a telescope with a magnification of 10x is a telescope that can magnify a target with a 1-degree angle of view to 10 degrees.

2. Field of view.

The field of view is marked with the visual range of the product at 1000 meters, such as 126m 1000m, which means that it is 1000 meters away from the observer, and the telescope can observe the field of view within 126 meters.

3. Exit pupil diameter.

is a parameter that roughly describes the brightness of an image. In low-light environments, the larger the diameter of the exit pupil, the clearer the image. The maximum human pupil, under normal physiological circumstances, will not exceed 7mm, so the diameter of the exit pupil greater than 7mm is inadvertently a waste of light.

4. Resolution.

Resolution is the precision of the screen image, which refers to the number of pixels that the display can display. Since the dots, lines, and surfaces on the screen are made up of pixels, the more pixels a display can display, the finer the picture will be, and the more information can be displayed in the same screen area, so resolution is one of the most important performance indicators.

5. Dusk coefficient.

Reflects the observation performance of telescopes with different aperture and magnification in low-light conditions. Calculation method: The product of the magnification and aperture of the telescope is squared.

6. Effective caliber and relative caliber.

The distance from the center of the objective to the focal point is called the focal length of the objective and is denoted by the symbol f. The part of the objective whose diameter is not obscured by the frame and diaphragm is called the effective aperture of the objective and is denoted by the symbol d. The performance of astronomical telescopes is mainly marked by these two data.

7. Light collection power.

In dark places, the diameter of the pupil of the human eye is generally about 7mm. Therefore, the multiple of the effective area of the telescope objective lens relative to the pupil area is called the light collection force. That is: light collection force = (d*d) (7*7), where d is measured in millimeters.

1. Meeting, drama, sports, outdoor activities, etc.: choose telescope products with a magnification of 6-8 times and a compact shape.

2. Ornamental birds: Choose products with a magnification of 7-8 times, a large objective lens diameter, and a compact telescope product.

3. **Outdoor games on large fields such as football: It is suitable to choose wide-field telescope products with a magnification of 7-8 times and an objective lens diameter of 20-50 mm.

4. Use at the water's edge or in a humid environment: Choose a telescope product with waterproof function.

5. Tourism, mountaineering, leisure: Choose products with a magnification of 7-8 times, a large objective lens diameter, and a compact telescope product.

1. Concert.

2. Sporting events.

3. Bird watching. 4. Outdoor sports.

5. Used by astronomy enthusiasts for stargazing.

About telescopes, just read this one!

1. The eyepiece is equivalent to a magnifying glass, which is upright and magnified virtual image.

2. The objective lens is equivalent to a camera, which is an inverted and reduced real image.

The first action of the telescope magnifies the opening angle of distant objects, allowing the human eye to see details with smaller angular distances. The second function of the telescope is to feed the beam of light collected by the objective lens that is much thicker than the diameter of the pupil into the human eye, so that the observer can see faint objects that were not previously visible.

The role of the telescope eyepiece is equivalent to a magnifying glass, and the role of the objective lens is to gather magnification, and then adjust it according to the visual acuity to make it more clearly displayed in front of your eyes Some people will feel dizzy when using a telescope, and it is best to look at it and rest.

Regardless of the type of telescope, the purpose of the objective lens is to bring distant objects closer to their focal length into a real image, and the eyepiece magnifies this real image to increase the viewing angle and see the details, remembering that the telescope magnifies the angle of view, not the distance.

Telescope: The objective lens is equivalent to a camera, which becomes an inverted and zoomed out real image;

The eyepiece is equivalent to a magnifying glass, an upright, magnified virtual image.

The three types of telescopes are refracting telescopes, reflecting telescopes, and catadioptric telescopes.

1. Refracting telescope.

A refracting telescope is a telescope that uses a lens to grow a mirror. There are two types: the Galilean telescope, which uses a concave lens as an eyepiece; A convex lens as an eyepiece is called a Kepler telescope.

2. Reflecting telescope.

The relative aperture of the reflecting telescope can be larger, the relative aperture of the main focus reflecting telescope is about 1 5-1, or even larger, and in addition to the Newtonian telescope, the length of the lens barrel is much shorter than the focal length of the system, and the primary mirror has only one surface to be processed, which greatly reduces the cost and manufacturing difficulties, so the optical telescope with aperture and hand greater than meter is all reflecting telescope.

3. Catadioptric telescope.

On the basis of spherical mirrors, the catadioptric telescope can be supplemented with refractive elements that are stupid to correct aberrations, which can avoid difficult large-scale aspheric processing and obtain good image quality. One of the more famous ones is the Schmidt telescope. It places a Schmitt correction plate at the center of the spherical mirror.

It is that one face is flat and the other is a slightly deformed aspheric surface, so that the central part of the beam is slightly converging and the peripheral part is slightly diverging, just correcting for spherical aberration and coma.

Telescope maintenance tips

1. Ensure that the telescope is stored in a ventilated, dry and clean place to prevent mildew.

2. The remaining dirty spots or stains on the lens should be gently wiped with a professional lens cloth to avoid scratching the mirror, if you need to clean the mirror, you should use absorbent cotton to occupy a little alcohol, wipe from the center of the mirror along a direction to the edge of the mirror, and constantly replace the absorbent cotton ball until it is clean.

3. The telescope is a precision instrument, and it is important not to fall, press or do other strenuous actions on the telescope.

4. Non-professionals should not try to disassemble the telescope and clean the inside of the telescope.

5. The use of telescopes should pay attention to moisture-proof and waterproof, and the telescope, as a precision instrument, should be avoided under harsh conditions as much as possible.

6. Do not collide with sharp objects, such as iron nails, needles, etc.