I grew accustomed to the notion that what one sees through a normal lens equates (or is close to) what can be seen with the naked eye (although that is not the "pure" definition of a normal lens, which is when the focal length and the sensor's diagonal are the same or close enough).
However, while playing with a zoom lens (on Canon APS-C, 1.6 crop) and keeping both eyes open, both views perfectly overlapped (and "merged") at 50mm (you get interesting effects when defocusing the lens at that stage, although you can't capture what you see).
That's a long stretch from what's considered normal on APS-C formats (between 25 and 35mm), so how could this be? Do full-frame DSLRs experience the same effect somewhere around 80mm?