Photographing optical system, image capturing unit and electronic device

A photographing optical system comprising five lens elements, the five lens elements being, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element, and each of the five lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;

• wherein the second lens element has negative refractive power, the fifth lens element has negative refractive power, and at least one of the five lens elements has at least one aspheric surface having at least one inflection point;
• wherein an axial distance between the image-side surface of the fifth lens element and an image surface is BL, an axial distance between the second lens element and the third lens element is T23, an axial distance between the fourth lens element and the fifth lens element is T45, 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 object-side surface of the first lens element and the image-side surface of the fifth lens element is TD, a focal length of the first lens element is f1, a focal length of the third lens element is f3, a focal length of the fifth lens element is f5, an f-number of the photographing optical system is Fno, a minimum value among Abbe numbers of all lens elements of the photographing optical system is Vmin, and the following conditions are satisfied:
• BL/T45<1.0;
• 0.45<(CT2+CT3)/T23<5.8;
• 3.9<TD/BL;
• 3.8<|f3/f5|;
• 1.00<Fno<2.60;
• 10.0<Vmin<22.0;
• |f5/f1|<1.0;
• and
• 0.45<T23/CT3<1.0.

A photographing optical system comprising five lens elements, the five lens elements being, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element, and each of the five lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;

• wherein the second lens element has negative refractive power, the fifth lens element has negative refractive power, and at least one of the five lens elements has at least one aspheric surface having at least one inflection point;
• wherein an axial distance between the image-side surface of the fifth lens element and an image surface is BL, an axial distance between the second lens element and the third lens element is T23, an axial distance between the fourth lens element and the fifth lens element is T45, 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 object-side surface of the first lens element and the image-side surface of the fifth lens element is TD, a focal length of the photographing optical system is f, a focal length of the third lens element is f3, a focal length of the fifth lens element is f5, a curvature radius of the object-side surface of the fourth lens element is R7, and the following conditions are satisfied:
• BL/T45<1.0;
• 0.65<(CT2+CT3)/T23<5.8;
• 7.0<TD/BL;
• 6.3<|f3/f5|;
• and
• −1.00<f/R7<1.40.