Manfrotto Advanced Tri Backpack Camera Case, Medium

A perfect backpack for carrying a DSLR sized camera, 3-4 lenses, flash, accessories, and an externally attached tripod is this one from Manfrotto.  It offers three ways to haul gear on adventures: backpack, sling (left or right shoulder) or X-position.  With adjustable padded inner dividers, you can custom fit the interior to perfectly protect gear.  Excellent zipper locations make it easy to quickly access gear in each compartment and the rain cover allows use in any weather condition.