1. How to choose a suitable binoculars
There are three factors to consider when choosing binoculars: aperture size, magnification and lens quality:
Aperture size: the size (diameter or aperture) of the objective lens (the lens in front of the telescope
facing the target), the binoculars on the market are more common with an aperture of 20mm to 70mm, for example, the telescope is marked with 12×25 25 means the aperture is 25mm (2, 5 cm), 12 means its magnification, the larger the aperture, the larger the volume, and the aperture size is greatly related to the light-gathering power (brightness) and resolution (definition) of the telescope, 12 x The 25 and 12×50 binoculars are also 12x, but the brightness and clarity of the latter must be higher than the former.
When you consider the aperture size of binoculars, there are no more than two choices:
1. If you are watching concerts, various ball games, mountaineering, outings, etc. Portability is a priority, and it is best to choose a model with a small and medium diameter (below 35mm), which is small in size and light in weight, but inevitably sacrifices brightness and resolution.
2. If it is astronomical observation, night or long-distance observation where high brightness and high resolution are the first priority, it would be ideal to choose a larger aperture. Heavy, long-term observation is easy to get tired. At present, most of the binoculars with medium aperture and above already have a tripod fixing hole design, which can be fixed on a general camera tripod, which can not only reduce the burden on the hands, but also greatly improve the stability.
Magnification: Most consumers consider the magnification first when choosing a telescope. They think that the higher the magnification, the better, but it is not correct. High magnification does not mean the image is clearer, and the aperture changes simultaneously Large, so the choice of magnification is good enough. The biggest advantage of binoculars is that they are easy to carry and have high mobility. If a higher magnification is required for long-distance observation, it is recommended to choose a ground-based monocular. The effect will be better. good.
Lens quality: This item is the most difficult for ordinary people to understand. The optical part of a binocular is composed of: 1. Objective lens. 2. Eyepiece. 3. Prisms. Combination, let’s talk about it first:
1. Objective lens: that is, the lens that is closest to the target at the front end of the two lens barrels of the binoculars. The quality of the image depends on the objective lens. There is a direct relationship between quality. Most of the general products are achromatic objectives composed of two lenses. A few high-quality binoculars use three combinations, or use special materials such as ED and fluorite to reduce the impact of chromatic aberration.
2. Eyepiece: When using a telescope, the lens group near the eye is called the eyepiece (left and right eyes). A typical eyepiece is composed of three optical lenses. The eyepiece itself The field of view is about 50 degrees, and the actual field of view is the field of view of the eyepiece divided by the magnification. If binoculars with the same magnification want to have a larger field of view and maintain a good image around the field of view, more lenses are needed, which is more complicated The design is revised, and the price is relatively increased.
3. Prism: If the telescope only has the combination of the objective lens and the eyepiece, the image seen is reversed up and down, left and right, so it is necessary to add the optical path between the objective lens and the eyepiece. A set of erecting prisms turn the picture we see through the telescope into the normal direction. The prism material is generally BAK-7 glass. More advanced models will use BAK-4 prisms with high refractive index to make the image brighter. . Binoculars with a straight-tube design must use a Roof Prism, which is more difficult to manufacture and usually has a higher price.
The above optical common sense will be helpful. The last three principles are for your reference when purchasing:
1. When you Considering the convenience of carrying and choosing a small model, the magnification should not be too high, otherwise you may be disappointed because the brightness is too low.
Second, you must understand the purpose of using a telescope? Choose the one that suits your needs the best.
Third, find a professional company to inform you of your purpose and budget in detail. I believe that as long as it is a dedicated professional company, it will give you satisfactory service.
2. Tips for buying binoculars
1. Tips for purchasing binoculars with optical effects
Generally, when we buy telescopes, we will see telescopes with the same specifications, but the price is very different. This is mainly due to the different coatings on the lenses of our telescopes, because it affects the optics of the telescope. good or bad. Generally, the brightness of military telescopes is the highest, and the brighter it is, the farther it can see.
The better the coating on the lens, the more transparent the lens and the darker the reflection. Another type of telescope is a red-coated telescope. The red coating of the lens can not only increase the brightness of the telescope, but also make the imaging more like. You can also choose this type of telescope.
2, functional shoppingTips
Nitrogen flushing inside the telescope has the effect of water, and can also prevent the internal lens from fogging and mold growth, which is mainly because the telescope is well sealed, so this increases the durability of the telescope. Let’s talk about the advantages and disadvantages of different prisms in the telescope. Generally, there are porro prisms and roof prisms. Although the Porro prism is large in size, it has a simple structure, high light transmittance and good imaging quality. As for the roof prism, although the volume is small, the structure of the prism is complex and the light transmittance is low.
3. Selection of telescope workmanship and materialTips
1 .It is made of all plastic.
2. It is a mixture of plastic and metal, and its main components are made of metal materials.
3. It is all-metal material, which is the best durability of the telescope among the three materials.