I just bought a new (to me) Anniversary Graphic and it came with a bunch of accessories, including a couple of pack film backs.

When did Kodak stop making 4x5 pack film? This packaging appears to pre-date my involvment in large format (1980 or so)... or was I simply unaware of a seemingly convenient film packaging?

And.. how did it work? There is a Plus-X Pack Film data sheet in the box and it seem like on put the pack into the back, put the back in the camera, puled the darkslide... then exposed, pulled a paper tab, etc. until all are gone. Then took the pack out of the back. Were they light-tight? How did the pack "flip" a new piece of film into the gate given the small package it appears to have been in? Was the film in pack films the same film as in sheet form?