Optical Lens System for Taking Image

An optical lens system for taking image comprising, in order from the object side to the image side:

• a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface;
• a second lens element with negative refractive power having a concave image-side surface;
• a third lens element with negative refractive power;
• a fourth lens element with positive refractive power having a concave image-side surface, inflection points being formed on the fourth lens element;
• and
• an aperture stop being located between an object to be photographed and the second lens element, an on-axis distance between the first lens element and the second lens element being T12, a focal length of the optical lens system for taking image being f, they satisfying the relation:
• (T12/f)*100>0.7;
• in the optical lens system for taking image, the number of the lens elements with refractive power being limited to four.

An optical lens system for taking image comprising, in order from the object side to the image side:

• a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface;
• a second lens element with negative refractive power;
• a third lens element with negative refractive power;
• a fourth lens element with positive refractive power having a concave image-side surface, inflection points being formed on the fourth lens element;
• and
• an aperture stop being located between an object to be photographed and the second lens element, a focal length of the optical lens system for taking image being f, a focal length of the first lens element being f1, an on-axis distance between the first lens element and the second lens element being T12, they satisfying the relations:
• 1.45<f/f1<1.80;
• (T12/f)*100>0.7;
• in the optical lens system for taking image, the number of the lens elements with refractive power being limited to four
• wherein an image-side surface of the second lens element is concave;
• the first lens element is provided with at least one aspheric surface, an object-side surface of the second lens element is convex, the second lens element is provided with at least one aspheric surface and is made of plastic material, an object-side surface of the third lens element is concave, an image-side surface of the third lens element is convex, and the third lens element is provided with at least one aspheric surface and is made of plastic material.