Why is the lens of the camera black? Isn't it opaque

This matter should be understood like this. ...

The function of the lens is to image. The best state is to penetrate all the light and project it on the image sensor for imaging. So, from the outside, it is black.

If it looks shiny, it means that the light is reflected back. How can it be imaged?

In fact, the lens transmittance of the lens is very high!