The problem was made clear to me a couple of years ago on an Icelandair flight from Baltimore to Iceland. Before boarding all standard carry-on bags were collected and checked. Passengers were only allowed to keep small backpacks. Fortunately my backpack was small enough. Now I have more equipment and this has become a pressing problem.
Hi,
I have lived overseas in a number of countries for years. Photography is my serious hobby and I travel worldwide with my gear. It goes in one place: carry-on. Except for very light on photographic gear it go in my Tenba PBP (Photo BackPack) with tripod strapped to its side. That is a larger sized photoback pack and one my most precious pieces of photographic equpment; discountinued by Tenba, but I also have a spare for future . Light weight, strong and not conspicious. At times when loaded it weights 12-15kgs. I have now also added a Tenba large messenger bag when I carry also my Shen-Hao 4x5, or for lighter travels when I use only the messenger.
How do I get it all on as carry-on? Stand with straight back in check-in line, friendly, courteous speaking and all else ready for them at check in. It is rare that I am given problems, but when I am I simply courteous insist to carry it onbord, explaining that I hace traveled worldwide with it, and also carried it onboard, and that thus is the international practice (written or not), that one camera (! ~ ?) and one computer is exempt from weight requirements. That indeed is the international practice, although I am not clear if it actually means one camera... vs. camera system. It also helps to have other baggage being light. Sometimes they ask how many cameras... of course I say... ~ 1.
Once they have started to enter you into their system at check-in, they are basically obliged to let you board the flight, or the flight will be delayed. If any problem I politely ask for the supervisor.
Above said, I travelled to Chicago on a business travel three years ago. Now how they could think that one Swedish and three Korean engineers could be suspect of terror I have no idea, or perhaps it was a random check. Horrible. Neither of us want to return. That time I only had a small camera with one lens, and a small duffle bag for luggage!
If it would have been me on that flight to Iceland, I would have done above, and... very possible is that they would have had to grant me an exception... or hold the flight. It is precious photographic gear we carry after all, and... checking it in is a risk, even more so these days when in some countries we cannot even lock our checked in luggage!
Regards
Anders