In reply to PPP:
I always carry my DSLR on a karabiner so that it goes on my harness(usually the R rear loop).Even if you are a walker you could put the camera on a karabiner and then clip onto a loop on your rucksac waist belt.
Just for fun,I have a Grivel locking karabiner which matches the Nikon colours.
Currently have a 10-24mm lens on the camera,but I usually have a wider set of focal lengths,but that lens is not functional at the moment..
I did used to take a superzoom,but it walked in or out too readily.(I understand that they have improved in recent years).
Rob