>take full frame pictures of classified documents on film roll - fast, easy.
>have to have specialised equipment set up somewhere with exact distances and focal lengths and precise cutouts and lighting and magnifiers and and and .... - slow, expensive, must be placed somewhere permanent like a safe house
>guard checking everyones shit between the general's room and the exit to my safe house.
How would this have been useful or practical? A dot is useful because it might be hidden in plain sight amongst other stuff on a picture if it was developed by spy-checkers, or it was useful because you might be able to fit *many* such dots on a single frame meaning useful compression of vital data in a small space but I fail to see how spies even got to the point where they were able to smuggle the important shit to where their equipment to do this was in the first place.
And if they could, why not just send the fucking normal roll of full frame pictured documents back to base as is? You can smuggle the obvious stuff out, why go through more trouble? Am I missing something here?
I cannot set up and then pack away all this equipment in the space of 5 mins in a high security area for the sake of miniaturization.