A change in 1 EV number doubles or halves the exposure. 1 EV up doubles; 1 EV down halves, thus a change of 1 EV is equivalent to a change of 1 stop or 1 shutter speed (modern shutters on 2x scale: 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, etc. Older shutters used 1/2, 1/5, 1/10, 1/25, 1/50, 1/100 which was not quite as close for the 1st & 3rd steps given here).(posted 8527 days ago)I think EV was originally designed to be on an absolute scale. Thus every meter should read the same lighting situation should give you the same EV number. I doubt, however, that you can count on this.