Back in the day (here we go again), we’d receive photo contact sheets—made directly from the photographer’s black and white or color negatives—that enabled us to review and select a final image. We’d use a loupe to see the details and photo croppers to determine, or verify, the final crop. Then we’d order up a print from the photographer.
Knowing your final image size, you could take the photographer’s print or transparency (35mm, 2.25″ or 4″x5″), lay your cropper on top, and determine the photo’s percentage of enlargement or reduction to be scanned for printing. Photo croppers—both small (above) and large—were never far from our drawing tables. Simple and easy to operate, they were a great invention. But like many such tools of the trade, completely unnecessary today.