Why is the photo taken in the studio half clear and half blurred?

Is the focus clear? If the aperture is very large (a large aperture is a small aperture value), then the depth of field of the photo is very limited, and everything is blurred to varying degrees except the focus. If the aperture is reduced, that is, the aperture value is increased, then the depth of field of the photo will be large and there will be more clear places.

Light is also related to focusing. If you use autofocus, the machine will automatically focus on bright areas, so it is best to focus on black objects manually.

The reflector is an indispensable object for photography, so it must be prepared. Many studios use white foam boards as reflectors to make the light softer.