add. ·adj not astigmatic;
said ·esp. of a lens system which consists of a converging lens and a diverging lens of equal and opposite astigmatism but different focal lengths, and sensibly free from astigmatism.
add. ·adj not astigmatic;
said ·esp. of a lens system which consists of a converging lens and a diverging lens of equal and opposite astigmatism but different focal lengths, and sensibly free from astigmatism.
Webster English vocab. Английский словарь Webster. 2012