I recently shot a story for Digital Photo magazine on portable power solutions for the photographer. How do you charge up that D4 battery when you are in woods? Hands down Goal Zero has been the answer for me. Goal Zero offers a large line of portable power packs and matching solar panels to power your gear in the field. Their power sources range from my favorite, the Sherpa 50, to the massive Yeti 1250 which can run your refrigerator. But here is the really handy thing; most of their large power supplies have inverters, which means you can plug in your camera charger just like you are plugging it into the wall. I use the Sherpa 50 to power up my batteries all the time, and recharge the battery during the day using the Nomad 13 solar panel. Better yet, this little pack can power Goal Zero Light-a-Life light for 16 hours, plenty of light to do work in camp at night. If you are looking for portable power, check out Goal Zero.