I know it's not supposed to be able to do that, but sometimes it does. For instance while sitting in a dark room and shooting down a well-lit hallway, it meters down the hall way with center AF point, but meters for the room when using the right-most AF point (on wall of dark room).
Yes, but that's evaluative metering weighting the exposure toward the selected AF point. It's not the same as spot metering. Does it give similar results in some situations? Yes...but then, a stopped analog clock shows the right time twice per day.
Ah, that's the key difference I was missing. So, it will bias the weighted measurement, but not perform a spot metering. Makes perfect since.
5D Mk III, Elan 7e, Nikon J1, some old rangefinders
Tamron 24-70 2.8 VC, 70-200 f/2.8L IS II, 400mm f/2.8L II, Sigma 85mm, 50mm, & 35mm f/1.4's, Rokinon 14mm f/2.8, Canon 2x Extender II, Kenko 1.4x, 430 EX II, Elinchroms