On long mountain walks, say Bag End to Rivendell, or in Norway Hølstoen to the big mountain Rindhatten,
bringing along them nice 20/1,8, 45/1.8, Tokina 100 micro and of course the 70-300 Nikkor,
do you
a) Keep them in wollen socks .. as suggested by Ken Rockwell
b) Keep them in leather pouches...