Optical image collecting system

An optical image collecting system comprising, in order from an object side to an image side thereof:

• a first lens element with positive refractive power having a convex object-side surface;
• a second lens element having refractive power;
• a third lens element having refractive power;
• a fourth lens element having refractive power;
• a fifth lens element with refractive power having a concave object-side surface and a convex image-side surface, wherein at least one of the object-side surface and the image-side surface of the fifth lens element is aspheric;
• and
• a sixth lens element with refractive power having a concave image-side surface at a paraxial region, wherein the image-side surface of the sixth lens element changes from concave at the paraxial region to convex at a peripheral region, and both of an object-side surface and the image-side surface of the sixth lens element are aspheric,
• wherein the said optical image collecting system has a total of six lens elements with refractive power;
• and
• wherein a focal length of the optical image collecting system is f, a focal length of the fifth lens element is f5, a vertical distance between a non-axial critical point on the image-side surface of the sixth lens element and an optical axis is Yc62, a central thickness of the third lens element is CT3, a central thickness of the fourth lens element is CT4, a central thickness of the fifth lens element is CT5, and the following relationships are satisfied:
• −1.3<f/f5<0.7;
• 0.15<Yc62/f<0.50;
• and
• 4.6<f/(CT3+CT4+CT5)<7.0.