The only potential issue with the 40mm is that its max aperture is only f/2.8, which isn't a problem on a modern DSLR but if you're shooting low light with film, it could be a bit restricting.
The 50mm lets in a bunch more photons and will make low-light situations easier to deal with.
The only potential issue with the 40mm is that its max aperture is only f/2.8, which isn't a problem on a modern DSLR but if you're shooting low light with film, it could be a bit restricting.
The 50mm lets in a bunch more photons and will make low-light situations easier to deal with.