由于散光，对象出现拉伸和扭曲。
散光是由于角膜时，形状像一个足球不定期。
Astigmatism is caused when the cornea is shaped irregularly like a football.
取景器盖能防止由于离散光进入取景器目镜而引起不正确的曝光。它能保证测光系统完全不受影响。 收藏。
The viewfinder cap is used to avoid incorrect exposure due to stray light which may enter the metering system is not adversely affected.
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