I am a photo backpack aficionado. I currently have about 10 different backpacks, which my husband Olof enjoys pointing out whenever a new one arrives from the UPS man. I just recevied from LowePro 2 very cool backpacks, which they are giving me in exchange for getting some shots of the packs in various locations. The first is the Lowe Pro Dryzone Rover.
It has a completely waterproof lower compartment that is very spacious and can hold my Hasselblad H3D with a zoom lens. It also has a hydration system so there is no need to carry an extra water bottle when using this pack. The upper compartment is not waterproof but is good for carrying clothing, lunch, etc. I plan to use this on an upcoming trip to Alaska where we will be doing some sea kayaking.
The other pack is a new one from Lowe Pro called the Vertex 200 AW.This pack is not waterproof but is water resistant and would be fine to wear in the rain. It is just the right size for me to carry the H3D with 3 large lenses. It is lighter in weight than my previous pack which was the burly Photo Trekker. It has a lighter waist band and shoulder straps and seems to have stiffer foam and exterior than the Photo Trekker. The accessory compartments are designed to hold digital cards and batteries. It will fit into an overhead bin on an airplane. I will be using this as my main bag for my upcoming trip to Maui.
It also has a cool tripod holding system. I also found a great case for various accessories & chargers, extra lenses, and the laptop computer - the Pelican D'Exec Wheeled Camera Attache. This is small enough to also fit in the overhead, and has a zip on laptop case for the front so that you can add that and still have only 2 carry ons with the Lowe Vertex backpack and this wheeled case. Since it is wheeled the Vertex can be placed on top of this case for easy rolling through airports, etc. This case seems very durable and it is deep enough to carry lots of gear without being to tall. I used to use a PorterCase hard sided case but felt that it did not have enough padding inside for rolling on pavement with sensitive equipment and was too heavy when empty. The Lowe Photo Trekker is a great pack but I find it too bulky for airport travel - it is more suited to long day hikes with alot of heavy gear since it has such an ample waist belt.