Originally posted by maxfield_photo What causes "normal" perspective is having a lens on your camera that matches the diagonal of the image area, either film or digital sensor. With 35mm film that diagonal was 43mm (or close enough), which is why Pentax made the FA43 limited, to give a true "normal" perspective. With an APS-C sensor the diagonal is more like 29mm, so a 28mm~31mm prime is about as close as you'll get, or a zoom set to 29mm.
Field of view is different though, many times you'll hear that a "normal" lens "represents what you would see with your eyes". That's only true in the sense of perspective, but since we have two eyes, and their "font elements", if you will, are shaped differently than a camera lens, our field of view is much greater. It varies a bit from person to person, but it's close to 180 degrees if you use both eyes.
[edit: I believe that when it comes to viewfinder magnification a 50mm lens is used, presumably because it was close-enough-to-normal on film, to calculate how large the image appears in the VF. Surprisingly, I don't think they changed that when smaller formats like APS-C, micro 4/3, and so forth were introduced.]
This isn't true. I have a 43mm limited, and it definitely expands the perspective from normal vision like a wide angle lens does. It's slightly wide angle. Things in the viewfinder appear
slightly further away with the 43mm, whereas, if you mount a 50mm and look though with your left eye, the perspective will be the exact same as your right eye on either APS-C or 135 SLRs.
The guy in the article says this is due to how the pentaprism is designed.
This is the phenomenon I'm talking about, not field of view.