The obvious answer would be to check with the airline and/or airports concerned. Chances are that it won't be a problem but if it is, make sure there's room in your bag (or pockets) for the camera and lens (make sure you've got a body and rear lens cap handy just in case they have to be split to go in a pocket!). I always wear a fleece with big pockets when flying so I can stuff any overweight from my hand luggage into the pockets if/when they weigh it and get snotty!