Zoom lens group

A zoom lens group, sequentially comprising, from an object side to an image side along an optical axis:

• a first lens group with positive refractive power, comprising a first lens with refractive power and a second lens with refractive power, which are sequentially arranged along the optical axis;
• a second lens group with negative refractive power, comprising a third lens with negative refractive power and a fourth lens with refractive power, which are sequentially arranged along the optical axis;
• and
• a third lens group with positive refractive power, comprising a fifth lens with positive refractive power, a sixth lens with refractive power, a seventh lens with negative refractive power and an eighth lens with refractive power, which are sequentially arranged along the optical axis, wherein both an object-side surface and an image-side surface of the fifth lens are convex surfaces, and both an object-side surface and an image-side surface of the seventh lens are concave surfaces;
• and
• positions of the second lens group and the third lens group on the optical axis are adjustable, an effective focal length f1 of the first lens, an effective focal length f2 of the second lens, an effective focal length f3 of the third lens and an effective focal length f4 of the fourth lens meet 2.5<(f2−1)/(f4−f3)<5.5.