SVBONY Eyepiece Eyepiece Set In General Purpose Eyepiece Set Focal Length FMC Ultra Wide Angle Telescope Accessories Astronomical Observation 1.25

【Standard Size】Standard 1.25" (31.7 mm) fitting diameter. Can be used with any astronomical telescope with a 1.25" focusing device. 【66°Ultra Wide Angle】The eyepiece with 66 degree apparent field of view and long eye relief brings you a comfortable viewing experience and provides a bright high contrast view. [Excellent optical quality] Built-in FMC multilayer coating on the high refractive index rhythm transmission surface minimizes chromatic aberration and provides a bright and natural view. [Set of four] A set of four focal lengths: 6mm, 9mm, 15mm, and 20mm, allowing you to freely observe objects of different distances and sizes. It is ideal not only for observing the moon, but also for observing medium-sized star clusters, large cloudy nebulae, and deep sky observations. [Safety Guarantee] Our products are sold in 11 countries and are widely recognized. There is a 2-month worry-free warranty, so if there is any problem or damage with the product, please feel free to contact us. We will always do our best to provide warranty service. Importance of the eyepiece The eyepiece is one of the most important components of a telescope. A single eyepiece can completely change the way a telescope looks. Even if the purpose of observation, gazing, or use is different, you can bring out the full potential of the telescope. Also, you can continue to use it even if you upgrade your telescope. Recommendation for wide-angle eyepieces When eyepieces have approximately the same focal length, the eyepiece with a wider apparent field of view will have a wider actual field of view. An eyepiece with a wider apparent field of view will allow you to experience a more spectacular "space walk." About the focal length of an eyepiece Relationship between the focal length of an eyepiece and magnification Magnification is determined by the formula: focal length of the objective lens (mirror) ÷ focal length of the eyepiece lens. Also, since the focal length of a telescope's objective lens cannot be changed, all magnification adjustments are made by replacing the eyepiece. As you can see from the above formula, the longer the focal length of the eyepiece, the lower the magnification, and the lower the focal length of the eyepiece, the higher the magnification. The lower the magnification, the wider and brighter the visible range; The higher you go, the narrower and darker the visible area becomes. During actual observation, stars are observed at the optimal magnification by changing eyepieces with different focal lengths depending on the object being viewed.