Mechanism for moving optical element of an optical system

A mechanism for moving a first optical element and a second optical element along an optical axis of an optical system, comprising:

• first and second guiding shafts disposed parallel to the optical axis and spaced apart to each other in a direction perpendicular to the optical axis;
• a first frame movable along the optical axis and supporting the first optical element, said first frame including first front and rear shaft bearings and a second shaft bearing, said first front and rear shaft bearings being disposed spaced apart to each other along said first guiding shaft and engaged with said first guiding shaft slidably along the longitudinal direction of said first guiding shaft, said second shaft bearing being engaged with said second guiding shaft slidably along the longitudinal direction of said second guiding shaft;
• and
• a second frame movable along the optical axis and supporting the second optical element, said second frame including third front and rear shaft bearings and a fourth shaft bearing, said third front and rear shaft bearings being disposed spaced apart to each other along said second guiding shaft with said second shaft bearing therebetween and engaged with said second guiding shaft slidably along the longitudinal direction of said second guiding shaft, said fourth shaft bearing being engaged with said first guiding shaft slidably along the longitudinal direction of said first guiding shaft between said first front and rear shaft bearings.