Optical imaging system

An optical imaging system, comprising:

• a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens disposed in order from an object side to an imaging side, wherein:
• the first lens is configured to have positive refractive power, and the second lens is configured to have negative refractive power;
• the third lens is configured to have positive refractive power, and the fourth lens is configured to have positive refractive power;
• the sixth lens is configured to have negative refractive power and a concave image-side surface in a paraxial region thereof;
• the seventh lens is configured to have positive refractive power, a convex object-side surface in a paraxial region thereof, and a convex image-side surface in the paraxial region thereof;
• and
• TTL/(2×IMG HT)<0.6, −0.2<SAG52/TTL<0, and 10<v1−(v6+v7)/2<30 are satisfied,
• where TTL is a distance from an object-side surface of the first lens to an imaging plane on an optical axis, IMG HT is equal to half a diagonal length of the imaging plane, SAG52 is a SAG value at an end of an effective aperture of an image-side surface of the fifth lens, v1 is an Abbe number of the first lens, v6 is an Abbe number of the sixth lens, and v7 is an Abbe number of the seventh lens.