What is the ruling on selling cameras if their owner knows of the prohibition of photography, and is selling them to a Muslim considered assisting in sin, and what is the ruling on the money earned from that?

Selling a studio that photographs both permissible and impermissible things is permissible. If it is used to photograph permissible things like cars, airplanes, and mountains, then there is no harm in selling it. However, photographing living beings is not permissible except out of necessity, such as photographing personal identity cards, passports, academic certificates, and criminals, due to the Almighty's saying: "And He has already explained to you what He has forbidden to you, except for that to which you are compelled." There is no harm in selling the studio if it is used for good, because it can be used for both good and evil, like a sword or a knife. The sin lies with whoever uses it for evil. However, if it is known that the buyer will use it for evil, then selling it to him is forbidden.