Employees working for your business under an employment contract will be creating work for your business and it will be owned by you and your business. This is covered in Intellectual Property Law and also should be mirrored in your own employment contracts. It is very important that your contracts make this clear to the employee as this will reinforce the rights of your business and possibly how they use the images taken by them. With freelance workers you should resolve any questions on ownership within your contracts as the law is more complex where there is no employment relationship. You cannot but admire them for asking and seeing the training as a route to fame and fortune!