I was looking though a copy of Flash! The associated Press Covers the World and had a few images where the DOF usage just seemed to make the images jump off the page for me. Now I'm trying to figure out what makes them feel so different to me.

For reference
Marathon Dancing - 1928
Rocking Horse - 1946

All the images that seem to have this aesthetic are all shot from the 40's and earlier, and have really nice detail with no grain, so I'm certain that the use of Large Format is in play here.

The backgrounds seem to get out of focus rather quickly, yet they don't look like photos taken at wide apertures with the focus set on the subject. Best idea I can come up with is that they could have been shot at smaller aperture, only focused close so that the subjects are placed more towards the back of the DOF? I think this would explain the wide swath of "infocusness", and account for the backgrounds being out of focus, but not the point that it looks like it was shot wide open.

Sound like a reasonable explanation? Anything else that could be a factor like older lens design? I'm just kind of curious since I'm going to do a band shoot in Minneapolis this weekend with a 4x5 and would love to try and get the same feel on some of the images if possible.