The detailed explanation of the parameters of the binoculars purchase method will answer you what kind of binoculars are good
We often hear friends who come to buy binoculars and ask: ‘You guys How far can your telescope
see?’, ‘How much can your telescope magnify?’, ‘How big can your telescope magnify the stars in the sky?’… Questions such as these reflect the public’s lack of telescope and astronomical knowledge.
The so-called ‘how far to see’ and ‘how much to zoom in’ are neither scientific nor meaningful, nor is the quality of telescopes judged in this way.
In fact, ‘how far to see’ depends entirely on the brightness of the object being observed. As long as the object is bright enough, it can be seen without a telescope. Seeing infinity, for example, about 6,000 stars that we can see with the naked eye can actually be considered to be infinity; and ‘how big’ is a question that is raised due to lack of basic knowledge of astronomy, because More than 99.9 percent of the ‘stars in the sky’ we see are stars, and the stars are so far away that even with the largest telescope on Earth, they are still just geometric bright spots (the smaller the bright spot, the more optical The higher the imaging quality; on the contrary, if you see a star with a surface or even a color in the telescope, it can be concluded that its optical system has serious drawbacks), only those celestial bodies in the solar system (such as the sun, planets, satellites, comets, etc. ) or celestial bodies with visible surfaces outside the solar system (such as nebulae, galaxies, star clusters, etc.) can only be magnified with the help of telescopes.
So is ‘magnification’ the first performance index to consider when buying a telescope? Absolutely not! Not only does it not rank first, but if the selection is too large, the image quality will be seriously deteriorated.
Magnification (preferably between 8x and 10x)
The telescopes are marked with the words 10 x 42, 8 x 30, etc. The former represents magnification, the latter representing the diameter of the objective lens. Using a 10x telescope to see a bird standing at 100 meters is as close as it is to the naked eye at 10 meters. Because the magnification is too large, the viewing angle is smaller, it is more difficult to search for the target, and it is easier to affect the clarity due to trembling of the hands. When the light is very sufficient, 10 times is clearer than 8 times; when the light is insufficient, 8 times can see details better than 10 times, so high magnification should not be blindly pursued.
Aperture (preferably between 30mm and 42mm)
The larger the aperture, the better. The diameter of the objective lens affects the amount of light entering. Especially in the case of strong contrast between light and dark, morning and evening, and cloudy conditions, the larger the aperture, the higher the amount of incoming light, and the eyes can see more details; but at the same time, the heavier the telescope, the more likely to cause fatigue when watching for a long time. It is advisable to choose a larger diameter according to individual physical fitness.
Field of view (the bigger the better)
The field of view refers to the range that can be seen from 1000 meters, and the width of the field of view should be higher than 104 meters That is 6 degrees. The larger the field of view, the faster and easier it is to find the target. However, the larger the field of view, the more serious the distortion and blurring of the edges, the more complicated and difficult the correction of aberrations, and the higher the required technology and cost.
Color fidelity (the more natural the better)
A high-quality telescope must faithfully reflect the primary colors and color saturation of the scene. In order to increase the brightness of the telescope, some manufacturers deliberately increase or decrease a certain light wave, which leads to distortion and makes the scene appear bluish or reddish.
The relationship between light transmittance and coating is inseparable, and directly affects color fidelity. All optical glass has high light transmittance and multi-layer coating on the whole surface, with high brightness and accurate color reproduction. Generally, manufacturers will not publish all the data (it is difficult to do so), and some manufacturers will publish the light transmittance or coating of local optical glass to mislead consumers.
Performance
Depth of Field
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For bird watchers, the depth of field is a relatively contradictory parameter. If the depth of field is large, frequent focus adjustment is not required, which is more convenient to use. However, for bird watchers, the foreground and background are not easily blurred. , the birds are not easy to stand out. And the depth of field is small, although the foreground and background blurred obviously when observing the forest birds, and the bird theme is prominent, but when the distance changes, it is necessary to refocus, and the fingers must always be on the focusing wheel, which is more tiring. It depends on personal preference, there is no set standard.
Sealing
Telescopes are often carried out outdoors, and the observation environment is changeable. In this way, the interior of the mirror can be kept sealed and stable, without fog and mildew.
Comfort
Comfort varies from person to person. Generally speaking, for the surface-coated telescope, not only the anti-shock effect is good, but also more comfortable to hold; the weight of the mirror body determines whether it is convenient to use and carry for a long time; usually, people will choose the telescope with high durability.