I just got a 100mm-400mm F4.5-5.6 and need to replace my Tamrac Expedition 3...I went to look at some bags and it seemed like if the camera/lens fit mounted with the hood reversed that it cut down on the room to each side so much that I couldnt fit anything on the sides....I know there are some large bags that would work but I want something that is more manageable to carry on my back....I was told that a Tamrac Expeidition 5x would work but the shop I was at didnt have one for me to see just how big it was....I wanted to see the 4x but they didnt have that one either...so I am curious as to what bag you are using with your 100mm-400mm and if you have pics of it mounted on your camera in the bag I would love to see pics
TIA


