Ask the photographer! Manual gear focusing problem

It's not that it's wrong, but that you don't know how to get there.

The focus of this photo is accurate. Your focus is on the waist of the model, which is very clear. Blurred head and feet are the result of poor image quality at the edge of the lens. This kind of composition, focusing is to focus on the face by pressing the shutter half-time, then compose the composition, and finally press the shutter to complete the shooting. What can be close-up gives priority to the eyes.