The word you're struggling with is "digitizing", not "digitalizing". It all depends upon the method used. If it is done frame by frame with a large optical sensor & a clean print, then the result can look as good as the original. If it is done merely with a 16 mm projector, screen & digital camcorder, the results will be disappointing. The frame by frame method is very tedious, time consuming & expensive.
As usual, fhotoace's answer is excellent advice.