Lens barrel

1. A lens barrel comprising:

a front holding member and a rear holding member which hold a front optical element and a rear optical element, respectively, said rear holding member being provided behind said front holding member in an optical axis direction;

an advancing/retracting member which is moved rearward in said optical axis direction when said lens barrel moves from a ready-to-photograph state to a lens barrel accommodated state, in which no pictures can be taken;

a first guide portion which guides said front holding member in said optical axis direction relative to said advancing/retracting member;

a first biasing member which biases said front holding member rearwards in said optical axis direction;

a second guide portion which guides said rear holding member in said optical axis direction independently of said advancing/retracting member;

a second biasing member which biases said rear holding member toward front in said optical axis direction; and

first contact portions provided between said front holding member and said rear holding member, respectively, a rearward movement of said front holding member due to a rearward movement of said advancing/retracting member causing said first contact portions to come into contact with each other to transmit a rearward moving force of said front holding member to said rear holding member against a biasing force of said second biasing member when said lens barrel moves from said ready-to-photograph state to said lens barrel accommodated state,

wherein said first guide portion, said second guide portion, a first force-applied portion provided between said first biasing member and said front holding member at which said first biasing member and said front holding member are in contact, a second force-applied portion provided between said second biasing member and said rear holding member at which said second biasing member and said rear holding member are in contact with each other, and said first contact portions are all positioned within one of four angular ranges about said optical axis which are defined by dividing 360° into four equiangular ranges as viewed from the front or back of said lens barrel along said optical axis.

2. The lens barrel according to claim 1 , further comprising:

a first stopper which is fixed to said advancing/retracting member and determines a rear movement limit of said front holding member with respect to said advancing/retracting member; and

a second stopper, a position of which in said optical axis direction is controllable, that determines a front movement limit of said rear holding member.

3. The lens barrel according to claim 1 , further comprising second contact portions provided between a rear member, which is provided behind said rear holding member, and one of said front holding member and said rear holding member,

wherein, during a retracting operation of said lens barrel from said ready-to-photograph state to said lens barrel accommodated state, said second contact portions come into contact with each other before said advancing/retracting member reaches a rear movement limit thereof to limit a rearward movement of said front holding member relative to said rear member one of directly and indirectly via said rear holding member so as to cause relative movement between said front holding member and said advancing/retracting member in said optical axis direction against a biasing force of said first biasing member, and

wherein said second contact portions are positioned within said one of said four angular ranges.

4. The lens barrel according to claim 3 , wherein said rear holding member comprises:

an optical element holding portion which holds said rear optical element; and

a radial arm which extends radially outwards from said optical element holding portion, a radially outer end of said radial arm being guided by said second guide portion, and

wherein said first contact portions include a first rear projection which projects rearward in said optical axis direction from said front holding member to be capable of coming into contact with a front surface of said radial arm.

5. The lens barrel according to claim 4 , wherein said second contact portions comprise a second rear projection which projects rearward in said optical axis direction from said front holding member to be capable of coming into contact with a front projection formed on said rear member.

6. The lens barrel according to claim 4 , wherein said second contact portions comprise:

a rear surface formed on said radial arm of said rear holding member, said rear surface facing rearwardly in said optical axis direction; and

an abutting surface formed on said rear member, said abutting surface facing forwardly in said optical axis direction to face said rear surface of said radial arm.

7. The lens barrel according to claim 3 , wherein said rear member comprises a stationary member which holds an image sensor so that said image sensor lies at an image forming position of an optical system of said lens barrel.

8. The lens barrel according to claim 1 , wherein said front optical element that is held by said front holding member comprises light quantity control elements which can be opened and shut, and

wherein said rear optical element that is held by said rear holding member comprises a lens group.

9. The lens barrel according to claim 8 , wherein said advancing/retracting member holds a front lens group provided in front of said light quantity control elements when said lens barrel is in said ready-to-photograph state,

wherein, when said lens barrel moves from said ready-to-photograph state to said lens barrel accommodated state, a movement of said front holding member relative to said advancing/retracting member in said optical axis direction causes said light quantity control elements, which are opened, to surround the outer periphery of said front lens group so that said light quantity control elements and said front lens group coincide with each other in a plane orthogonal to the optical axis.

10. The lens barrel according to claim 1 , wherein each of said first biasing member and said second biasing member comprises a spring.

11. The lens barrel according to claim 1 , wherein said second guide portion comprises:

a guide shaft extending in said optical axis direction; and

a guide hole which is formed through said rear holding member and in which said guide shaft is inserted.