coarse adjustment knob
/ˈkɔːs ɐdʒˈʌstmənt ˈnɒb/
n
English · coarse adjustment knob中文 · 粗调旋钮Español · botón de ajuste gruesoFrançais · vis macrométrique
Bedeutung：Medium-precision focusing device for adjusting the distance between the objective and the object under study.