Why is having the correct bag so important? Look at any pro and chances are that he has more than one bag. It's not luggage but a vital piece of equipment that protects and allows quick access to your gear. I usually use a shoulder bag when it is convenient and I need access to a lot of gear. However, when the going gets tough, my chest pouch allows me to rapidly access my DSLR, and have it protected unobtrusively against my chest.
Galen Rowell is something of a mentor to me. He was a pioneer in landscape and adventure photography in remote wilderness using 35mm equipment. He favored functional, lightweight and robust gear. In the eighties, I used a chest pouch that Galen recommended. It was small, light, and fit a manual Nikon with a small lens. Galen used stretchy Optech camera straps such that the camera straps would come out of either side of the chest pouch when the top flap was closed with Velcro. The pouch was held around your body with a light strap that would prevent the pouch from falling away when you removed the camera. More information can be found on Galen’s Mountain Light Website and his 2001 article: Running With A Camera.
A good chest pouch is hard to find these days. Since the eighties, cameras have grown in size and weight and I’ve been looking for a replacement ever since I got my Canon XT 350D. Most of the chest pouches I’ve seen are either too bulky with excessive padding and interfere with my movement, or use zips instead of Velcro to secure the pouch and cannot be accessed rapidly. The best solution I’ve found is in the Newswear line of bags. Their lightly padded body pouch, although designed to hold a Pro DSLR body without lens, will tightly contain a Canon XT 350D (or XTi 400D) with a 10-22mm or 17-85mm IS lens in the manner described above. It is a compact bag, so if you are using a bigger body like a 5D or Nikon D200, I think you are out of luck. Please let me know if you are using a different body and this works for you.
If I need a spare lens, it can go in an accessory pouch that rides next to the chest pouch. By the way, if you need a compact lens pouch, Newswear makes a Strobe Pouch (designed to fit a flash) that fits my Canon 70-300mm IS USM lens just fine. Don’t bother to ask Newswear, because they will probably tell you that it won’t fit. Just bring your stuff down to the store and try it yourself. Newswear’s website is available here.
The straps on the Newswear Pouches are sized large enough to fit on the hip belts of most backpacks. You can also unclip the camera strap and wear the pouch on your hips holster style. The pouch front pockets will hold some accessories such as a gallon size ziplock bag (in case of rain), lens cloth and a polarizing filter.
I last met Galen in Nepal in October, 1997. It was a chance encounter that set up lunch with Galen and his wife, Barbara. The previous day, from a taxi along the crowded streets of Kathmandu, I saw a familiar figure with his camera. I yelled out to Galen and, of course, there was the puzzled look on his face as he tried to recall who I was. The next day, while walking along the streets, we bumped into Galen and his wife, Barbara. By this time, he recalled who I was, even though we had only chatted briefly in his office about a year earlier, and he generously invited us to lunch with them. That’s the kind of guy he was, and that’s how I’ll always remember him.
Top: Here I am wearing the Newswear Body Pouch containing my Canon 350D with a 10-22mm lens. It really is very low profile. Normally, I would have to swing the pouch to the side in order to see my feet, but as you can see, I have my hands full. This bamboo bridge is more precarious than it looks. Each of my feet is on a different bamboo pole that flexes independantly. Picture taken by my wife, Laura.
Bottom: top row, left to right: Lowepro Topload Zoom 65 AW (enormous, reserved for my future 1D/2D), 'Galen Rowell' Chest Pouch ('80s), Newswear Strobe Pouch with Canon 70-300 IS USM. Bottom row: Sundog camera holster ('90s), Newswear Body Pouch with Canon rebel XT 350D next to it.
Update Feb 18: The Nikon D80 with Nikkor 18-200mm just fits, but it's a bit of a squeeze.