I believe that a camera is additional to the cabin baggage allowance, as are binoculars and a few other odds and ends. Worse case scenario is that you take them out for the weigh in and then put them back in after. Whether your carry on gets weighed depends very much on the airline and/or handling agents. Generally, if the bag doesn't look too big and it isn't a roller, they won't weigh it. But that is not 100% guaranteed, especially if the check-in agent is new or under training.