| 摘要 |
PURPOSE:To focus an object point of the infinity with a plastic lens even if the temperature is changed, by changing a detaining position in accordance with the temperature by a pin 9 of a holding ring, to which a bimetal is attached, and a stopper of the barrel having steps. CONSTITUTION:A pin 9 of a holding ring 2 for the first lens group consisting of a plastic lens is so provided that the projection height of the pin 9 is changed in accordance with the variation of temperature by a bimetal 11. A stopper 10 of a barrel 4 has the height changed in steps considering the movement difference of the lens for the variance of temperature. Therefore, the detaining position between the pin 9 and the stopper 10 is changed in steps in accordance with the variation of temperature. Thus, since the plastic lens is detained in the position corresponding to the temperature even if the focal length of the plastic lens is changed by the variation of temperature, the object point of the infinity is focused in the position where the holding ring 2 is turned all out. |
