This might be a basic printing 101 lesson question but I felt worth asking here.
I have been scanning 35mm film and selected some for prints. My issue is that if I just crop for best content this rarely fits with the various printing paper ratios. The paper ratios of course vary with size so it seems to me that the final crop ratio has to be made with the expected size that I am outputting. My experience is if I don't select this, the printer will crop for me, and the final output not what I had in mind.
So should I be cropping to suit the print size AND that prints size's ratio?
What about metric vs imperial measurements of paper? Is there much concern there?