For film cameras, holding exposure time times f-stop constant does not produce the same image density. Exposure time for film is not straight photon integration, like it is for a CCD array. You can only trigger each film grain once, but new photons can repeatedly add electrons to a single CCD pixel. So there's what's called "reciprocity failure".[1]
Then you get an analogue NOT operation when printing the negative on the enlarger. Two negative processes make a positive.
Film photography is very interesting as it combines art with optics and chemistry. Just pure magic seeing the image fade into the paper when developing.
Vision3 50D was recently(for film) introduced in 2011, and I had amazing results with it. Super smooth with very good latitude.