These glass filters can crack unexpectedly from overheating when the telescope is pointed at the Sun, and retinal damage can occur faster than the observer can move the eye from the eyepiece.

• 这些镜后减光的太阳滤镜会因阳光聚焦的高热而随时爆裂；观测者的视网膜会在迅雷不及掩耳的速度下受到伤害.