Here is a review I wrote several months ago for my then newly acquired
Tamrac Expedition 5 backpack. This relatively compact (12.75in/32cm wide x 16in/41cm tall x 10in/25cm thick) backpack features solid construction, good padding, and comfortable fit. Since the main compartment interior is slightly thicker at the top (6-6.5 inches) than at the bottom (5-5.5 inches), the Pentax K10D with battery grip sits very nicely in the top-center of the bag as intended by the manufacturer. I typically leave a 18-250mm zoom lens, with lens hood extended, permanently attached to the camera.
After the camera and zoom lens, there is still room for several smaller lenses or a larger lens with two or three smaller lenses, a Pentax AF-540FGZ flash with accessories (diffusers, etc.), perhaps a spare camera body (depending on the number of lenses), a handful of filters (square or round in cases), spare battery and charger, angle viewfinder, and small accessories (cords, straps, etc).
The two smaller "winged" pockets on the outside of the lid are too small and shallow to hold much securely. The tiny pockets inside do hold the K10D battery and memory cards, but AA batteries tend to fall out easily if not contained in an plastic baggie or something before placed inside.
The K10D's owners manual fits nicely into either one of two areas; the bottom fiber-reinforced clear plastic pocket on the inside of the lid or the larger zippered pocket on the outside of the lid. In fact, the large zippered pocket on the outside of the lid is big enough to hold the owners manual, a one-inch thick paper-based organizer, and a light jacket or wind-breaker folded flatly.
There are two Modular Accessory System (MAS) slots on each side of the backpack, allowing up to four MAS compatible items to be attached (pouches, water bottle holder, etc). And four Strap Accessory System (SAS) slots on the shoulder straps, allowing for four SAS compatible items (cellphone or MP3 player pouch, etc). Two strap holders on the bottom of the backpack could be used to carry a larger jacket or tripod (extra straps not included, but the tripod straps on the lid could be moved to here). A jacket could also be bungied to the slot attachments on the top and sides of the backpack.
I added a pair of Tamrac N-11 quick-release camera straps to the metal d-rings on the shoulder straps of the backpack, eliminating the need for an additional neck strap for the camera. The quick-release connectors fit all Tamrac quick release straps. Since I don't like waistbelts, I cut off the included canvas waist strap (slight melting the tips to prevent fraying). I also shortened some of the longer straps so they wouldn't drag on the ground while the backpack is carried by hand (leaving plenty to extend over heavier clothing). I also removed the quick-release chest strap fitted between the two shoulder straps.
Finally, I added a newly purchased "Velbon Ultra MAXi F" tripod (14-inches folded) to the side of the backpack - instead of the lid to balance better on my back. This is a very nice little travel tripod, by the way. It's clearly not as steady as a heavy-duty tripod, but good enough for most situations especially with legs spread slightly, not fully, while handled like a monopod. I replaced the pan/tilt head with a Velbon PH-353 ballhead, increasing the folded length to about 16-inches but stronger to better support the heavier Pentax K10D.
All of this makes for a reasonably compact travel setup only as heavy as the number of items added.
stewart