If you love to experiment in photographic techniques, or if you are a professional photographer, you probably need to travel with a very complete equipment. You can buy very good photographic bags of the type with interchangeable dividers, or you can build yourself a personalized backpack.
Step 1: the bag
With that purpose I've bought a good quality rock-climbing backpack, which is used to keep all the equipment to reach the starting point of the ascension. This bag has many advantages, it's very capacious, it opens completely, it's light and it has the exact dimensions of the hand luggage on the planes. And, differently than professional photographic bags, it doesn't appear as a gravy train for thieves!