Patent ID: RE44773

Claim:
An optical imaging system comprising an image sensor for photoelectric conversion, the optical imaging system further comprising: a first lens group having a positive refractive power closest to a subject an object ; a second lens group closest to the first lens group and having a negative refractive power; a third lens group having one of a positive or negative power; and a fourth lens group having one of a positive or negative power, wherein the first lens group comprises an aspheric lens having both surfaces aspheric and each of the first second to fourth lens groups comprises an aspheric lens having at least one aspheric surface thereof; and one of a thin film filter or an optical filter for restricting the transmission of a portion of light between the second and third lens groups or between the third and fourth lens groups , wherein a first lens of the first lens group has an object side surface having a positive curvature, and a second lens of the second lens group has an image side surface having a positive curvature and a third lens of the third lens group has an object side surface having a negative curvature and an image side surface having a negative curvature .