Dual lens optical system and digital camera module including the same

A dual lens optical system including a first optical system and a second optical system includes at least one reflection member to selectively redirect object lights in first and second directions toward a photographing device. The first optical system includes, in order from an object to the photographing device along the optical axis, a first lens group comprising a first reflection member, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power. The second optical system shares at least one optical element with the first optical system.