The telescope is a kind of travel necessary items, but also people watch concerts and large-scale sports games necessary supplies.  Since a telescope is an instrument for looking at distant places, its purpose is to place large objects on easy observation with as little loss of detail as possible.  That is, the ideal telescope should “magnify objects losslessly, restoring true detail”.  I’m a telescope lover myself, and I have a collection of several different telescopes, especially the Apexel ones, which are inexpensive and meet my basic needs.  Today the old driver with their own experience and we say how to pick a telescope.  

1. How to pick a telescope? 

(1) Look at optical parameters  

The aperture of the telescope: the aperture of the telescope is one of the most important parameters of the telescope, the larger the aperture of the telescope, the higher the theoretical resolution, the higher the light-gathering ability (the brightness is higher when the same multiple), but at the same time the volume and weight of the telescope will be larger, the price will be higher, hand-held telescopes are generally 20-50mm. 

 However, it should be noted that some low-quality telescopes are shielded by prisms and have too small light bars inside, so the actual aperture is smaller than the nominal value.  The brightness of the telescope is also related to the quality and performance of the coating, and a small, high-quality telescope can often be more efficient than a large, poor telescope.  

Find tong diameter of a telescope: the diameter of the telescope divided by multiple values is called the exit pupil diameter of the telescope, that is, the diameter of the beam of the telescope from the eyepiece.  This number is not usually labeled on the telescope, but can be easily calculated. 

 At the same time, you can directly measure the telescope eyepiece, the objective lens is facing the light, the eyepiece away from a certain distance, then you can see a bright round spot, the diameter of the round spot is the diameter of the exit pupil of the telescope if it is not very round with cut edge indicates that the prism is not good or not big enough.  The multiple apertures and exit pupil diameter of the telescope can be calculated by knowing two of them, so we can verify the accuracy of the telescope’s nomenclature.  Formal product labels are mostly very accurate. 

The exit pupil diameter of the telescope directly determines the surface brightness of the object seen by the telescope. The larger the exit pupil diameter is, the higher the brightness is, which is proportional to the square of the exit pupil diameter.  But when the exit pupil diameter is larger than the pupil diameter of the eye, some light that does not enter the eye is wasted, and the effective aperture of the telescope becomes smaller.  

Telescope field of view: many people have a misconception, the same magnification, the same aperture telescope field of view is the same.  Essentially there is no necessary connection between the three.  

You all know that the field of view of a telescope is very important to the observer, and the bigger the field, the better it is to use.  

The field of view of a telescope is affected by four parameters: the internal structure of the telescope, the objective aperture of the telescope, the eyepiece aperture of the telescope, and the multiple of the telescope.  

(2) Look at the design  

Portability: portability mainly depends on the weight and volume, the general weight of the telescope within 300g is more convenient to carry, and the roof structure is more convenient to fold and carry, T01 in portability is the biggest advantage, the weight is only 190g, the volume of 87*104mm, side hanging rope design, these are designed for portability.  Paul mirrors with the same optical parameters tend to be larger.  

Maneuverability: maneuverability mainly depends on three aspects, namely pupil distance adjustment, focusing wheel, eye mask adjustment, and diopter adjustment.  Pupil distance adjustment range — adult pupil distance is generally 58- 64mm.  The pupil distance of children is generally 50~60mm.  So when buying binoculars, be sure to distinguish between adults and children.  The T01 telescope has an eye distance adjustment of 56 to 72mm, which indicates that it is an adult telescope.  

If you’re buying a telescope for your teenage son but don’t want to buy a child’s telescope, measure the distance between the child’s eyes and choose a telescope with a downline that covers the distance between the child’s eyes because the distance will get wider and wider as the child grows.  

Stability: stability mainly depends on product sealing, structural stability, etc.  From the sealing point of view, generally mainly depends on the installation method of the objective lens eyepiece, the size of the gap, is enough to fill nitrogen waterproof and fog-proof.  T01 objective lens fixed ring is a fixed way of non-opening fixed point glue. This structure is common in the focusing design of roof lenses, but it does not use nitrogen filling waterproof and fog-proof, so it is not suitable for outdoor hiking and other occasions.  

In terms of structural stability, the fixed-power telescope is more durable than the variable-power telescope, and the roof structure is a little more durable than the Paul structure.  In addition, the gripping sense of the telescope, the weight of 300g to 500g is the best grip sense, too lightweight is too small size, but easy to shake in use.  

2. Last word  

First, shop around and pick up a few brands before deciding which brand to buy.  

Second, although the higher the telescope rate, the clearer the picture, the selection should be taken into consideration in many aspects, because more than ten times the telescope, and then hold the hand to see, you will find that the picture is very shaky.  

Third, if the purpose of buying a telescope is to use it when playing in the countryside, it is best to choose a telescope with a multiplier of fewer than 10 times, otherwise, it will be tied up in its trap.  

Fourth, here mainly observe the main telescope material and the lens material, we should avoid those with inferior plastic as the main body of the telescope in the selection.  

Fifth, the better the quality of the telescope is more expensive, the common telescope on the market, the price from dozens of yuan to tens of thousands of yuan, we can according to their economic ability, choose the corresponding price of the telescope.