A person presumed to possess the legal capacity for consent cannot have sex with a person presumed to lack that legal capacity. The teenager is not restricted; the adult is restricted.
When a camera is added, the law becomes inconsistent. The minor lacks the capacity to legally engage in sex, but is now (potentially) culpable in their own exploitation if they video themselves.
Teenagers having sex is legal, sharing pictures of it is not.
A person presumed to possess the legal capacity for consent cannot have sex with a person presumed to lack that legal capacity. The teenager is not restricted; the adult is restricted.
When a camera is added, the law becomes inconsistent. The minor lacks the capacity to legally engage in sex, but is now (potentially) culpable in their own exploitation if they video themselves.