I currently use a Canon 5D with 5 lenses accompanying it, the largest being the 100-400 Canon telephoto. The rest are of moderate size. I could be getting two or even three more lenses here shortly, and the choices are overwhelming as far as bags to accomodate the lenses and DSLR body. Overwhelming in that I'm frightened I'll spend hundreds of dollars on the wrong bag. Say I'm in Manhattan or Chicago's loop or wherever else, taking urban wide-angles, urban-fisheyes, and urban telephotos, all within a close period of time. That's a lot of lens changing. (And a lot of time for dirt to get inside and on my sensor too! ) As I was saying, it is very cumbersome to go through the following set of procedures: 1) Mount wide angle 17-40 to camera body, close bag, put bag on back. 2) Get my wide angle shots 3) See some things that would look great with the fisheye 4) Take bag off back, lay on ground in busy urban sidewalk, dismount wide angle lens, mount fisheye lens, close bag, put bag on back again. 5) Get my fisheye shots 6) Oh, but damn! Look down that huge "urban canyon" streetwall of tall buildings - perfect for telephoto-induced urban chaos and drama! So, take bag off of back again, dismount fisheye, mount telephoto, close bag, bag goes back on my back yet again... mind you this is all happening within a manner of minutes, and it's a really pain and incredibly inefficient. What can I do? Slider backpack that holds 6 or 7 lenses and a DSLR body? Does such a thing even exist? Could I throw a Mac Book Pro in there too!? Can I carry it on a plane? Can I switch between wide angle and fisheye and telephoto and prime and all that possibly without having to remove the backpack from my back for EVERY SINGLE LENS CHANGE? Or some combination of lesser backpack but use a bag at the waist in addition to the backpack...? advise, plz. k thx.