My small Lowe Pro 15L carries 4-5 lenses, Chamonix 45N2, polarizer, R72, 10 stop ND and a deep yellow filter with all the needed step up rings plus a couple of grads. It also holds water, snacks and spare clothing lashed to the outside. With my carbon fiber tripod, light ACRA-tech GP head and various other goodies, 6 film holders and a roll film or Kinematic 10 exposure back, the whole setup weighs in at 22 pounds. Over the years I have noticed how a light pack plays a big role in how long I can stay out, where I can go and how dynamic the resulting photos are.