Gowland Pocket View 4x5 are the lightest you can get. They also pack very small. They are monorail type- so you can remove the rail stow it, then let the camera lay flat. Very safe and easy way to store- you don't need any special expensive bags either- just put in a plain old backpack and it's fine. Even if you fall you are unlikely to break a camera like this since it's all aluminum.