I generally prefer to use full-sized sheet film, but rollfilm backs can be convenient for travel. For example, I just returned from a week backpacking in the high Sierra, where I had to take hike up to 12000 ft twice, and 1000 once, all in the same week, and then return right
back to work without a rest day. When I was a teenager in my mid-40's, I had no trouble hauling an 85 pound pack up all the peaks and passes. But now I'm in my mid sixties, so have basically wimped out, and carried only about 65 lbs. What prompted that decision is that I am
down to my last boxes of Readyload and Quickload film sleeves, and am saving them up for a different trip. Plus I like the elongated format of
6x9. And a 300mm lens with this format gives me about the same perspective as 450 with 4x5. The down side is that it is a lot fussier focusing and setting the tilts and swings with the smaller format, and the degree of enlargement is obviously somewhat less. But I have way
too many full 4x5 and 8x10 shots on hand anyway, for those really big prints. The introduction of Ektar was a game-changer in this respect
for me. Of course, since this is being done with a 4x5 camera to begin with, I can still elect to carry along a couple full-sized filmholders, or
leave some in the picnic box in the truck for road shooting on the way home (which I did a bit of)... Just nice to have options. A changing
tent for 4x5 doesn't add that much weight, but weather conditions don't always work out, and in this particular instance I was in a regulated
area where bear canisters had to be carried, so I didn't have a lot of space left in the pack.