The field of view is the range that can be seen through a telescope. The larger the field of view, the larger the observation range. The word "154m / 1000m" means that you use this telescope to observe the scenery 1000m away from you. The maximum range that you can actually see up and down is 154m. This is an angle relationship, and the farther you go, the greater the distance. So sometimes you'll see that the field of view is expressed in terms of angles, such as 8 ° 30 'and so on. The larger the aperture, the lower the magnification.