We're generally responsible for damage we cause to things that belong to other people. You should look at the documents you signed, if any, when you signed up for the class and/or when you checked out the camera. Do they mention your responsibility for damage or loss to their equipment? If so, then they have a good argument that you have to live up to the terms of that agreement. And if you were negligent--that is, maybe you grabbed the camera wrong, or didn't have the strap wrapped around your wrist, or something like that--then even if their insurance covered it, they might have a claim against you for the damage.
If you have homeowner's or general-liability insurance, it may cover the damage if you owe it, but of course that may affect your future premiums.
Even if they have insurance, and that insurance company pays for the camera, the insurance company could then come after you for whatever they pay. This principle is called 'subrogation'. So, even if they have insurance you are not off the hook.