I noticed the portrait had the black border, which indicates the unexposed bit of film between the shutter and the sprocket-holes above and below, and the little buffer either side between the adjacent photos. this is only found on film shot on rolls. the older, long-exposure photos were on individual glass plates and fully exposed, no “border.”
but I didn’t really think all that through until I read your post.
[which brings up a pet peeve of mine: traditionally, seeing the black border was “proof” that the shot was composed by the photographer as they took it. it was not a wild shot that was later cropped to fix the composition. people adding a black border to their pics in photoshop to make them look arty or old fashioned get the bozack]
ETA: also just wanted to mention that Käsebier wasn’t just some random photog, she was one of her time’s heavy-hitters, I remember that name from my art history classes.
