They were way ahead of their time. Bear with me for this explanation. To quote [1], > f-number of an optical system such as a camera lens is the ratio of the s

They were way ahead of their time. Bear with me for this explanation. To quote [1], > f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture"). In other words, this is a relative number. And as far "being sharply in focus" (stated reason for f/64 style) is concerned, for the same field-of-view angle, smaller sensor would require proportionally more open f-stop number to exactly match the look. 2-inch sensor with 90-degeree f/2 lens, would produce exact same depth-of-focus as 4-inch sensor with 90-degree f/4. According to [2], Adams was using 6,5×8,5 inch negatives around the time (let's call it 8 inch "sensor"). Compare that to the 1/2 to 1/4 inch sensors [3] of iPhone 13. So what aperture latter would need to exactly match the picture f/64 group wanted? (1/64) × 8 / (1/2) = 1/4 = f/4 (1/64) × 8 / (1/4) = 1/2 = f/2 As luck would have it, f/2 is pretty much bang-on the aperture of the same iPhone. In other words, when you take a photo with a current-gen smartphone, that photo would have, give or take, exact same depth-of-focus that group f/64 wanted. Everyone is group f/64 now. [1] https://en.wikipedia.org/wiki/F-number https://en.wikipedia.org/wiki/F-number [2] https://en.wikipedia.org/wiki/Monolith,_the_Face_of_Half_Dome#Location https://en.wikipedia.org/wiki/Monolith,_the_Face_of_Half_Dom... [3] https://www.dpreview.com/articles/6780391159/all-apple-iphone-13-and-13-pro-camera-upgrades-explained https://www.dpreview.com/articles/6780391159/all-apple-iphon...