1. Field of the Invention
This invention relates to a lens barrel, and more particularly to a lens barrel capable of the so-called onehand zoom in which focusing operation can be accomplished by the rotation of an operating ring about the optical axis and magnification changing operation can be accomplished by the displacement of the operating ring in the direction of the optical axis and capable of focusing operation to a very short distance, namely, macro operation.
2. Description of the Prior Art
What will hereinafter be described is generally known as a lens barrel of this type. That is, at lens barrel which comprises a focusing lens system as a first group, a variator lens system as a second group, a compensator lens system as a third group, and a master lens system as a fourth group and in which, during focusing operation, the focusing lens system is displaced in response to rotation of the operating ring and during magnification changing operation, the variator lens and the master lens are displaced while varying the spacing therebetween in response to displacement of the operating ring. Macro operation is accomplished by further rotating the operating ring beyond the short distance position thereof for focusing to a short distance and displacing the compensator lens system and the focusing lens system with this rotation. More particularly, when the operating ring is rotated beyond the short distance position thereof, the focusing lens system is displaced while, at the same time, an interlocking member operatively associated with the operating ring is coupled to a displacing member for displacing the compensator lens system, so that the rotational force of the operating ring is converted by the displacing member to displace the compensator lens system. When the operating ring is returned to the short distance position, the coupling between the interlocking member and the displacing member is released and therefore, only the focusing lens system is displaced by the rotation of the operating ring between the short distance position and an infinity position in which the system is focused to infinity. This lens barrel has the advantage that one can shift from focusing operation or magnification changing operation immediately to macro operation. This lens barrel, however, requires a clutch mechanism for bringing the interlocking member and the displacing member into and out of engagement with each other at the short distance position as described above, and this has led to the complicated construction of the lens barrel.