The 70mm back took cassettes could take about 15 feet of film and you could get about 50-60 shots per cassette. one daylight load cassette had the film and an empty cassette would be the takeup spool. They made nikkor tanks and spools for development. You could get everything you needed just like 35mm or 120. It's nice to be able to shoot 60 frames without reloading. You could get film in cassettes directly from kodak, or buy 100 foot rolls and
bulk load you own with a alden bulk loader