I was in a Timbuk2 store the other day looking for the same kind of bag and even though pricey their snoop camera bag looks and feels nice. I actually tried my camera with a slightly smaller lens that you mentioned and feels comfortable while carrying.
you can check from this link.They have various sizes. http://www.timbuk2.com/tb2/products/search-results/snoop-camera-messenger
Slashdot Mirror
I was in a Timbuk2 store the other day looking for the same kind of bag and even though pricey their snoop camera bag looks and feels nice. I actually tried my camera with a slightly smaller lens that you mentioned and feels comfortable while carrying. you can check from this link .They have various sizes. http://www.timbuk2.com/tb2/products/search-results/snoop-camera-messenger