SV182 Comfortable to Observe 15mm eye relief lets the wear-glasses astrophotography enthusiasts observe comfortably without taking off the glasses. In addition, proper eye relief effectively reduces eye fatigue for long-term observation.Observation and photography of the moon and planets, astronomical observation, astrophotography. The imaging principle of the MAK astronomical telescope: since it is a reflection of light and there is no dispersion of light, chromatic aberration in imaging is a concern for the entire optical system.