Ben:


A beltpack can be useful, but the Speed Racer may not fit in a backpack, unless the backpack is huge. The Speed Racer is [url="http://www.thinktankphoto.com/ttp_product_SpdRcr.php]officially[/url] 12.5" x 9" x 11", but it's really bigger than that, as those dimensions don't include the belt. You can stuff the belt into a slot on the back of the Speed Racer, but it's still bulkier than those dimensions. I took a few shots with my Canon G9 of my Speed Racer, loaded to the gills. (It weighs about 18 pounds loaded.)


Outside:








You can see from the ruler that it's really longer than 12.5" when packed. Here's a shot with the lid open. Note the belt is on top--that's the side toward the user's body. This may also give you an idea of just how big the Speed Racer is. Think Tank makes two similar, but smaller, beltpacks, the Speed Freak and Speed Demon, but they won't hold a "pro" DSLR (or one with a battery grip) like the Speed Racer can. I have large hands are really need the BG-E2 grip to be able to hold the 30D comfortably.











On the left is a Canon 100-400mm L IS lens with tripod ring and hood reversed. (The 70-200mm f/2.8L fits, as well.) On the right is a Canon 30D with the BG-E2 grip, with a Canon 17-85mm IS lens attached, also with the hood reversed. The 30D also has a Really Right Stuff L-plate, which makes it a bit wider and taller.


The upper parts of the dividers fold down to make a shelf for the camera. If you don't have a grip, the camera can go in the middle. I could also put it in the middle by turning it around, but it fits better this way, as the top of the camera is narrower than the grip. Next shot is without the camera.











Yes, this is flipped around--it's the way I see the bag when I'm carrying it. I did these on my porch. It was slightly raining and I didn't have a lot of room to maneuver. At the bottom of the hole on the left are a lens hood for the Sigma 10-20mm, a 77mm stack cap set with several filters, and a small Giottos Rocket blower.


In use, I will often leave the lid open and put the 100-400mm lens with
the hood deployed and the lens cap off "upside down" from the photo. It
could go that way normally, but it fits better this way because fo the
bulk of the camera. When I have another lens on the 30D, I put the 17-85mm in the hole on the left. (I have the tripod ring on the 100-400mm because I often use it with a monopod and it's a lot more stable with the monopod attached to the tripod ring than to the camera. I have a Kirk Arca-Swiss-type quick-release clamp on the monopod, which holds either the Wimberley P20 lens plate on the lens and the Really Right Stuff L-plate on the camera. That's a lot quicker to use than screwing the monopod into the ring and camera sockets. Sports photographers usually do screw the monopod onto the lens plate of their long lens--e.g., 400mm f/2.8L IS, as they probably have another camera body with a shorter (e.g., 70-200mm f/2.8L) lens. Even if they do have to change the lens, they can easily unmount the camera from the lens and leave the lens attached to the monopod. Bird photographers often do the same with a tripod. However, I have only one camera body.


Last shot, with the divider top flipped over to show what's underneath.











In the center compartments are, on the "front" (away from my body) a Canon 1.4x expander on top of a Sigma 10-20mm lens. (The Sigma won't fit in there with it's hood reversed, so the hood, which is only marginally useful, at best, is in the left compartment.) In the other compartment is a Canon 100mm f/2.8 Macro lens with a hood reversed. (It's not the usual ET-67 hood--which I have--but the shorter ET-67B, which doesn't get in the way as much when shooting macro and is easier to fit in a bag.)


This is with the removable foam insert in the bag. You can take it out to make the bag roomier--there is velcro for the dividers on the inside of the bag. (You might need to do this with a 1D or 1Ds with an L-plate attached.) The insert does provide some extra protection. It attaches to the "back" of the bag (lower side above) with velcro, but is not attached on the "front" (top of the photo). I use that gap to keep two BP-511 batteries and several Singh-Ray filters. (The Cokin P holder and ring are in the front pocket, along with a slew of other stuff.) There are also two CF card slots--you can see the blue edge of one. The red loop has the rain cover attached to it. If the weather is good, you can leave the rain cover out to reduce the bulk. On both sides of the bag are stretchy pockets, with mesh pockets over them. I usually keep an extra body cap and rear lens cap in one stretchy pocket and various stuff, like the hat above, in the mesh pockets, which have drawstrings. (The other one often has sunscreen and insect repellent, which I don't want inside the bag, plus sunglasses.) <span style="text-decoration: line-through;"]There are stretchy pockets on the front, where I put lens caps and other stuff temporarily. (No, there aren't! I was confusing the Speed Racer with the Change Up, which I carry a lot more often.) In the back, just outside where the macro lens is, is a pocket sized for a reporter's pad and pencil. I do keep a small notebook there.


When I carry the Speed Racer, I use both the shoulder strap diagonally across my body and the belt. The belt has rails for Think Tank's modular gear.


Lowepro makes a combination backpack-beltpack, the Orion AW, that may be worth checking out. The beltpack goes under the backpack--it looks like a regular backpack when the beltpack is attached. If you don't carry a lot of photo gear, the Think Tank Rotation 360&ordm; I mentioned before is another option, as is Think Tank's Change Up, which is a much slimmer beltpack. It holds the 100-400mm or 70-200mm f/2.8 comfortably with the removable insert out, plus some combination of two of: 580EX flash, two stacked prime lenses (e.g., 50mm f/1.8 &amp; 85mm f/1.8) and my Optura 50 camcorder, but it doesn't hold the camera with lens attached. You can add a Chimp Cage for the camera body, as well as other modular bits. At horse shows, I carry the Change Up plus the camera on the strap.