My Canon T90 has a 1/2 stop discrepancy between spot and center weighted metering modes. <p> With the entire field of view on a flat and constant illumination blank wall, the spot meter reading will result in 1/2 stop more light (e.g. 1/15 @ f/4) than the center weighted reading (e.g. 1/15 @ f/4.5). <p> This doesn't seem right to me. Can anyone confirm/deny this as normal operation? <p> Thanks!