Image capturing system

An image capturing system comprising, in order from an object side to an image side:

• a first lens element with positive refractive power having a convex object-side surface at a paraxial region;
• a second lens element with negative refractive power having a concave image-side surface at a paraxial region;
• a third lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at a paraxial region;
• and
• a fourth lens element with negative refractive power having a concave image-side surface at a paraxial region, wherein the image-side surface of the fourth lens element has a convex shape at a peripheral region, and both of an object-side surface and the image-side surface of the fourth lens element are aspheric;
• wherein the image capturing system has a total of four lens elements with refractive power, a central thickness of the second lens element is CT2, a central thickness of the third lens element is CT3, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, an axial distance between the third lens element and the fourth lens element is T34, a curvature radius of the image-side surface of the second lens element is R4, a curvature radius of the object-side surface of the third lens element is R5, and the following relationships are satisfied:
• 0.5<CT3/CT2<1.7;
• 0<(T23+T34)/T12<1.0;
• and
• 0<R4/R5.