Unless you have other hard, sharp objects bouncing around in your backpack you can always get a large padded lens wrap and just wrap the camera and lens together and toss it in your pack. This has worked for me at times with my Mamiya 7 and 80mm. Otherwise any small field camera bag will work as a bag-within-a-bag.
I use the option Jonathan mentions: I have a very small Domke SLR bag, no side-pockets...and the Mam6+lens fits with room to spare for a filter or two... Works quite well. Also, for day hikes from campsite, you can just bungee the smaller bag to your waist, and it's dust-free as you hike around...
I use the option Jonathan mentions: I have a very small Domke SLR bag, no side-pockets...and the Mam6+lens fits with room to spare for a filter or two... Works quite well. Also, for day hikes from campsite, you can just bungee the smaller bag to your waist, and it's dust-free as you hike around...