An endoscope comprising: - a substantially cylindrical housing, which is designed to be introduced into a body to be examined; - an optical focusing and zooming device contained in said housing; - motion imparting members contained in said housing, operating on said optical device and designed to move part of said optical device for its focusing and zooming operation; - transducer members located in said housing downstream from said optical device and designed to convert an optical flow focused by said optical device into an electric signal; - lighting members comprising at least one light source located in the housing; - a control and monitoring unit, which is designed to receive signals representative of optical zoom degrees and is operably connected to said motion imparting members to actuate said motion imparting members according to the received optical zoom-representative signals; - said optical device comprising a first set of lenses designed to cause an input optical flow to converge toward a second set of lenses, said second set of lenses being located downstream from said first set of lenses and being adapted to be moved by said motion imparting means toward and away from said first optical set and to change the overall optical zoom; a third set of lenses located downstream from said second set of lenses and adapted to be moved by said motion imparting members toward and away from said second optical set and to adjust focus; characterized in that the optical device further comprises a fourth set of lenses for focusing the optical flow from the third set of lenses on said transducer members; the distance between said first and fourth sets of lenses being unchangeable. - a substantially cylindrical housing, which is designed to be introduced into a body to be examined; - an optical focusing and zooming device contained in said housing; - motion imparting members contained in said housing, operating on said optical device and designed to move part of said optical device for its focusing and zooming operation; - transducer members located in said housing downstream from said optical device and designed to convert an optical flow focused by said optical device into an electric signal; - lighting members comprising at least one light source located in the housing; - a control and monitoring unit, which is designed to receive signals representative of optical zoom degrees and is operably connected to said motion imparting members to actuate said motion imparting members according to the received optical zoom-representative signals; - said optical device comprising a first set of lenses designed to cause an input optical flow to converge toward a second set of lenses, said second set of lenses being located downstream from said first set of lenses and being adapted to be moved by said motion imparting means toward and away from said first optical set and to change the overall optical zoom; a third set of lenses located downstream from said second set of lenses and adapted to be moved by said motion imparting members toward and away from said second optical set and to adjust focus; characterized in that the optical device further comprises a fourth set of lenses for focusing the optical flow from the third set of lenses on said transducer members; the distance between said first and fourth sets of lenses being unchangeable.