Patent ID: 6710931
Filing Date: 2004-03-23
Classification: G02B

Abstract:
A zoom lens comprising, in order from an object side to an image side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power, and a fourth lens unit of positive refractive power, wherein said first lens unit has a negative lens located on the most object side thereof, and said negative lens located on the most object side of said first lens unit satisfies the following conditions:(a) 35n<65, and (b) when 35n<52, âˆ’0.013 &ngr;11n+2.1911nn+1.92, when 52n<60, 1.511nn+1.92, when 60n<65, 1.511nn+2.94, where &ngr;11n is an Abbe number of a material of said negative lens located on the most object side of said first lens unit, and N11n is a refractive index of the material of said negative lens located on the most object side of said first lens unit,wherein said first lens unit has a second negative lens other than said negative lens located on the most object side thereof, and said second negative lens satisfies the following conditions: (c) 35n<65, and (d) when 35n<52, âˆ’0.013 &ngr;12n+2.1912nn+1.92, when 52n<60, 1.512nn+1.92, when 60n<65, 1.5<N12nn+2.94, where &ngr;12n is an Abbe number of a material of said second negative lens of said first lens unit, and N12n is a refractive index of the material of said second negative lens of said first lens unit,wherein the separation between adjacent lens units varies during zooming, and wherein no lens is present between (a) said negative lens located on the most object side of said first lens unit and (b) said second negative lens.