As I understand it, "normal" perspective has nothing at all to do with the width and height of the image when looking through the viewfinder. I see a larger FOV with one eye than I can see at 16mm on my K20.
The view through my viewfinder at about 55mm (roughly 80mm full-frame equivalent) shows objects in the focal plane at roughly the same size as my naked eye. This also has nothing to do with a "normal" perspective.
Perspective: The relationship of aspects of a subject to each other and to a whole.
"Normal" perspective in photography simply means that the relative size of the objects in the frame are reproduced in the same relative size as we see with our normal vision. If I look at a scene through a 16mm lens, the objects furthest from the focal plane of the lens look proportionately smaller compared to objects in the focal plane. If I look at the same scene at 250mm, the objects further back from the focal plane look proportionatly larger compared to objects in the focal plane.
Photographers use this effect in selecting "portrait length" lenses. The most
accurate portrait will be obtained with a normal lens. A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner. Hence the preference for mild telephoto portrait lenses. If you're photographing a beautiful model with an unusually long nose, pull out that 300mm prime.