hi jamie
the #3 is like the low budget version of the #5

1 f-stop, instread of the big button and a shutter release for it
a knurled knob you wiggle for the plates to fall i( it always gets jammed ! ) instead
of that funky key you turn and the plates always fall ... and best of all, when you unload the plates and load them there is like a tray that pulls out
and a big bed spring to give pressure so they fall. the #5 has that ingenius design where the floor drops out so you can pull the plates out.
i originally got my #5 for the septums, thinking they were the same as the #3, but as luck has it, they are completely different. thin metal instead of the thick ones in the cheap version.
i have 12 septums for my #5, and 8 for my #3, i've also thought of making some but i'm too lazy and broke to follow through. i've never shot film in them, just paper negatives and glass plates
i'm thinking of switching to plexiglass dry plates so i dont' have to worry about the plates breaking after they fall. and i ALWAYS serach for septums, and never have found any, and i am too broke to
pony up the $$ for a whole new #3, someone must be reading my blog cause they cost about 3-5 times as much as i paid for the whole lot.
if i see any septums i'll send you a note !
john