1) Depth of Field
For bird watchers, the depth of field is a relatively contradictory parameter. If the depth of field is large, there is no need to adjust the focus frequently, which is more convenient to use. However, for the observation of forest birds, the foreground and background are not easily blurred, and the birds are not easy protrude. And the depth of field is small. Although the foreground and background are blurred 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.
At present, all the so-called auto-focusing telescopes on the market are realized by improving the depth of field. In fact, there are no real auto-focusing telescopes on the market. The real auto-focusing telescopes require batteries as power and a built-in chip to determine the target to achieve. . There is currently no such telescope on the market. In other words, with auto-focusing telescopes, the foreground and background are not easily blurred, which will affect the observation of small distant targets such as birds (which are easily confused with the background).
Telescopes are often carried out outdoors, and the observation environment is changeable. It is best to choose a telescope that can prevent water immersion (water pressure and waterproof), so that the interior of the mirror can be kept sealed and stable, without fog and mildew.
Comfort varies from person to person. Generally speaking, for telescopes with plastic surface, not only the shockproof effect is good, but also it is 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 telescopes with high durability and performance.
Therefore, when buying a telescope, it is recommended to choose a metal structure and a plastic-coated telescope. This telescope is strong and can be used for input.