… and I have seen other pros that are fantastic, that don’t have a spare. It makes me worried but that’s their gamble.
I shot a wedding a couple of weeks ago on a beach at Key West, FL. I flew down with a big backpack full of gear then packed a smaller bag with what I thought would be useful at the beach and left the rest on the ship. After the ceremony and reception lunch, I switched to my backup camera for some candid photos on the way back to the ship. I doubt anyone noticed that I changed cameras. If you are walking around with two cameras on your shoulder, it is obvious but hardly anyone notices a black bag stuck in a corner and even fewer are curious, or brazen, enough to look inside it. It could be lenses, flashes, or a whole system.
The other photographers were a husband and wife team from LA. I think they each had a single 5D Mk II. That arrangement let them cover bride and groom simultaneously and during the wedding one shot long and the other short which also had benefits. If a camera failed, only one of them would still be working, but they would still get photos. Spare everything, including photographer.
Digital camera bodies are tough though. This video shows a 7D is really strong, or that Kai is crazy… http://www.digitalrev.com/article/canon-7d-hardcore-durability-test/MjA0MjMyMTE_A