Imaging system, image capturing apparatus and electronic device

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

• a first lens element with positive refractive power having an object-side surface being convex in a paraxial region thereof;
• a second lens element with negative refractive power having an image-side surface being concave in a paraxial region thereof;
• a third lens element having refractive power;
• a fourth lens element with refractive power having an image-side surface being concave in a paraxial region thereof, wherein an object-side surface and the image-side surface of the fourth lens element are aspheric, and the image-side surface of the fourth lens element comprises at least one convex shape in an off-axial region thereof;
• and
• a fifth lens element with refractive power having an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof, wherein the object-side surface and the image-side surface of the fifth lens element are aspheric, and the image-side surface of the fifth lens element comprises at least one convex shape in an off-axial region thereof;
• wherein the imaging system has a total of five lens elements with refractive power, there is an air gap between any two of the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element that are adjacent to each other, a central thickness of the fourth lens element is CT4, an axial distance between the third lens element and the fourth lens element is T34, an axial distance between the fourth lens element and the fifth lens element is T45, a focal length of the imaging system is f, a curvature radius of an object-side surface of the third lens element is R5, a curvature radius of an image-side surface of the third lens element is R6, an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, and the following conditions are satisfied:
• CT4/T34<1.20;
• CT4/T45<1.60;
• |f/R5|+|f/R6|<1.10;
• and
• 1.75<(V2+V4)/V3.