blackened inner-tube : The inner-side of refractor, including the optical tube, dew shield , draw tube, mirror diagonal are internally matte blackened, to avoid internally antireflection.

• 内部消光处理：望远镜内部，包括主镜筒，遮光罩，调焦筒，天顶镜等光路经过部分内壁都进行多重特殊工艺消光处理，避免杂散光线干扰影响成像。