What is the difference between a "press pack" and a "duplex film holder" used for photographic film?

[Micah Mileto]

I'm trying to understand the issue with the brain photographs. I know John Stringer said he never used Ansco film, which is the brand of film used for the brain photographs in the official collection today. But he also said he didn't use a "press pack" and instead used a "duplex film holder". What does that mean, and what is the difference between the two? Search engines are not helping me visualize the difference. 

[Micah Mileto]

So far, all I'm getting is that "press packs" are thin with numbers displayed while "duplex holders" are thick and unnumbered.

[James DiEugenio]

https://www.worthpoint.com/worthopedia/ihagee-patent-duplex-x-12-folding-408215497

I actually remember these kinds of cameras.

 

Compare to this. https://en.wikipedia.org/wiki/Press_camera#/media/File:Mpp_VIII.jpg

Edited November 15, 2020 by James DiEugenio

[Micah Mileto]

13 hours ago, James DiEugenio said:

https://www.worthpoint.com/worthopedia/ihagee-patent-duplex-x-12-folding-408215497

I actually remember these kinds of cameras.

 

Compare to this. https://en.wikipedia.org/wiki/Press_camera#/media/File:Mpp_VIII.jpg

Thanks, but do you know how press film holders are different from duplex ones?

[Richard Price]

Micah, I have only dabbled with photography and bought and sold vintage cameras, but I think the difference in plain terms is that a "press" film holder holds uncut (a roll) of film and the film is used by advancing from one section to another until you reach the end of the roll.  A "duplex" holder holds a cut sheet of film which has a positioning cut so you know which way to insert it into the camera and you have to put film into the holder for each photo.  This type is generally used for medium and large format pictures as opposed to 8mm, 16mm, or 35mm types.