The portable single telescopes can be generally divided into two categories: one is the specialized bird watching mirror, the other is the small diameter astronomical telescope converted to it.
The two kinds of mirrors are small caliber, generally between 50-80mm, and easy to carry. At the same time, the magnification rate is usually about tens of times, and then smaller, it has no advantage for binoculars. Once larger, the field of vision is too dark. This rate exceeds the stable range of human handheld grip, and needs to cooperate with the tripod. The observation is required under the ground scene, standing like a. In general, bird watching mirrors make up all positive images by prism. Astronomical telescopes can also make up a full image by adding a positive prism, but more of them use a 90 degree zenith prism or reflector, which is the opposite of the upper and lower sides. Almost all astronomical glasses and part of bird watching glasses can be connected to the SLR through interface accessories, and can be photographed as a manual telephoto lens.
In order to ensure portability, the mirror doesn't work very long. The ordinary achromatic lens will have a more obvious color difference, such as the impact of imaging, high-end products in order to improve the quality of the use of ED (ultra low dispersion) glass or stone and other special optical materials processing lens, the quality of the image has increased, the price is more than double, from one thousand or two thousand to at least four thousand or five thousand.
The difference between the two kinds of telescopes is that the bird watching mirror is generally used as a fixed or special eyepiece, and the focusing mechanism is also made into one. Some mirrors can be used for waterproof and nitrogen filling and easy to use. Astronomical mirrors cannot be sealed, but because the 90 degree ceiling is reflected only once, the optical path is much simpler and less image quality than the prism, so generally the same grade of astronomical mirror is a little better than a bird watching mirror. Besides, the eyepiece of the astronomical scope can be selected wider, and the eyepiece with better performance, field of view, sharpness and other better performance can be used.
The main brands of bird watchers are three in Europe: Zeiss, rhenka, Skei Ed Lloss Chi, and one for ten thousand or twenty thousand yuan. Japan's Nikon, Pentax, Kowa, Vixen and so on, the price of products of ED materials 5000-10000 yuan. In recent years, some domestic optical manufacturers have launched their own bird watching mirror products, ED mirrors do less than 5000 yuan, one thousand or two thousand yuan of ordinary materials, is the choice of comparative economy.
Small caliber astronomical mirror import high-end brands are Televue, TMB, Takahashi, Borg, and so on. In recent years, many domestic manufacturers, such as XinDa, Yuzhong, Rui Xing and Bo crown, are also producing ED mirrors, and some models have a good price performance. There are also a class of swords that use the small diameter Mark SUTO Rivka Zagrean type mirror instead of the refracting mirror, and the price is relatively low.
How many budgets should be taken into account when buying, what kind of structure is required, what are the requirements for the material brand, or not the single counter shooting, and so on, according to which to choose the model to buy. No matter which one you buy, you'd better compare it with the local astronomers and bird watching fans in advance. Or at least in other forums to see more new constellation of evaluation. Then buy it through a store or Taobao. In addition, for telescopes and optical products, there is a sentence called "one cent, one point, 10 Fen cents, three yuan." Performance is not linear with price. Find a balance point that you can accept.