So I've been noticing recently while having to manually focus a 50mm f/1.8D that 90% of the time the lens will appear super sharp in the viewfinder, but not be in focus in my actual image. Is there a good way to calibrate the viewfinder so that I can get a good idea of what's in focus and what's not? I'd like to avoid using the live view as much as possible, and the green focus light is sometimes too much to pay attention to while trying to frame a scene. Thanks!
Edit: Essentially what I'm wondering is if the diopter adjustment is going to help with this, or if that's simply for the in-eye interface focus.