The ideal camera bag is one that fits physically, and systematically into your photography. As such, you'll want to give careful thought to how you carry your gear. Since I shoot a wide variety of subject matter, I required a versatile and rugged solution. I also wanted something with a waist strap to take some of the weight burden off my back. Before finding the right bag, my shoulders would ache after long hikes in the woods. Rather than leaving necessary gear at home to shed weight, I started to research photo backpacks. In particular, the Lowepro Mini Trekker AW has enough room to fit a camera body with attached 400mm lens, plus a 70-200mm, a 100mm Macro, a Flash, various filters, batteries, and accessories. It also includes a rain cover for surprise downpours, padded shoulder straps, and a supportive waist strap. Best of all, it qualifies as a carry-on for both domestic and international flights.
When flying, I never want to check my expensive photo gear for fear that it could be broken or stolen. This two bag system has made air travel much easier. The backpack is my one carry-on piece of luggage while the holster qualifies as a small personal bag. They both fit under the seat, or in the overhead compartments.
My tripod is the only piece of photo gear that gets checked. Since it can be used as a weapon most airlines have policies against bringing then on board as a carry-on. Of course it's an essential piece of gear that can't be left behind. Here's how I transport it:
First, I remove the ball head and pack that in my carry-on photo backpack. Without the ballhead the tripod is a few inches shorter and fits inside a duffle bag. I then pack all of my clothes around the tripod and wrap it with a few sweaters or pants. This extra padding will protect it from being destroyed when it's tossed on and off the luggage belt. Should this bag get lost or stolen, I'll still have all of my camera gear and the clothes on my back.