Electronic device including optical system having a telephoto lens

An optical system comprising:

• a first lens group that has a positive refractive power;
• a second lens group that has a negative refractive power;
• a third lens group that has a negative refractive power;
• a fourth lens group that has a positive refractive power;
• and
• a fifth lens group that includes one or more lens groups, in sequence from an object,
• wherein the first lens group and the fifth lens group are fixed and the third lens group moves parallel to an optical axis to perform focusing when adjusting a magnification of the optical system from a wide-angle end to a telephoto end, and
• wherein the optical system satisfies the equation:
• |fT/f12T|<0.3,
• where fT represents a focal distance of the whole system at a telephoto end, and f12T represents a composite focal distance of the first lens group and the second lens group at a telephoto end.

An optical system comprising:

• a first lens group that has a positive refractive power;
• a second lens group that has a negative refractive power;
• a third lens group that has a negative refractive power;
• a fourth lens group that has a positive refractive power;
• and
• a fifth lens group that includes one or more lens groups, in sequence from an object,
• wherein the first lens group and the fifth lens group are fixed and the third lens group moves parallel to an optical axis to perform focusing when adjusting a magnification of the optical system from a wide-angle end to a telephoto end, and the third lens group is configured with one of one lens and two combined lenses, and
• wherein the optical system satisfies the equations:
• |fT/f12T|<0.3 and
• 0.4<|(R1+R2)/(R1−R2)|<0.8,
• where ft represents a focal distance of the whole system at a telephoto end, f12T represents a composite focal distance of the first lens group and the second lens group at a telephoto end, R1 represents a radius of curvature of the first lens surface from the object in the third lens group, and R2 represents a radius of curvature of the last lens surface from the object in the third lens group.

An optical system comprising:

• a first lens group that has a positive refractive power;
• a second lens group that has a negative refractive power;
• a third lens group that has a negative refractive power;
• a fourth lens group that has a positive refractive power;
• and
• a fifth lens group that includes one or more lens groups, in sequence from an object,
• wherein the first lens group and the fifth lens group are fixed and the third lens group moves parallel to an optical axis to perform focusing when adjusting a magnification of the optical system from a wide-angle end to a telephoto end, and the third lens group is configured with one of one lens and two combined lenses, and
• wherein the optical system satisfies the equations:
• |fT/f12T|<0.3
• 0<(wT(0.1)−wT(0))/wT(0)<0.15,
• where fT represents a focal distance of the whole system at a telephoto end, f12T represents a composite focal distance of the first lens group and the second lens group at a telephoto end, and wT(M) represents a degree of a half-angle of view at a telephoto end when the object-to-image magnification is M.

An optical system comprising:

• a first lens group that has a positive refractive power;
• a second lens group that has a negative refractive power;
• a third lens group that has a positive refractive power;
• and
• a fourth lens group that includes one or more lens groups,
• wherein the first lens group and the fourth lens group are fixed when adjusting a magnification of the optical system from a wide-angle end to a telephoto end, and the second lens group comprises a focusing lens group that moves parallel to an optical axis to perform focusing, and
• wherein the optical system satisfies the equation:
• |fT/fl-focusT|<0.3,
• where fT represents a focal distance of the whole system at a telephoto end, and fl-focusT represents a composite focal distance from the first lens group to a lens group before the focusing lens group at a telephoto end.