If we take a look, a 50mm equivalent lens is usually the smallest in size pretty much universally among different manufacturers. I wonder why this is so? I get the notion that longer focal length lenses are usually longer and wider lenses are usually wider in size, but why is the "minimum point" 50mm equivalent and not 35mm for example? I see that the the 50mm is called "normal" and it's supposed to be the closest focal length to stereoscopic human vision but I'm not sure if that has anything to do with the lens size. If I could hazard a guess, it has something to do with the standard 35mm film (size)?