①The expression of telescope magnification: 7*50, 8*40, etc., the front number indicates the magnification, the back number indicates the aperture, the unit is mm, 7*50 means the magnification is 7 times, and the objective lens aperture is 50mm.
②Magnification. The magnification should not be too high, because too high a magnification is easy to shake and the target cannot be seen clearly. 7-8 times is the best, because a high magnification means that the field of view is relatively narrow and the viewing field is very narrow.
③The 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 dusk, and cloudy, the larger the aperture, the higher the light input, the more details the eyes can see; but at the same time, the heavier the telescope, long-term observation is more likely to cause fatigue. It is advisable to choose a larger caliber according to personal physical fitness.
④The 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 or 6 degrees. The larger the field of view, the quicker and easier it is to search for 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, the higher the technology and cost required.
