SKY ROVER Ultra Flat Field 10mm eyepiece (hereinafter referred to as UF10 eyepiece) has compact mechanical design, provides high-quality optical imaging, can obviously improve the eyepiece field curvature, and control the edge distortion within an ideal range, and can obtain good imaging even on the main mirror with fast focal ratio. UF10 is equipped with a foldable eye cup, and friends who like to observe eyes are not easy to have black eyes.