that is adding nearly .20 second to all the times. Rifle and pistol, draw or raise and fire, and repeat hits, too. LOST the earlier prescription glasses, which the timer PROVED were faster to get the hits with. So now it's a choice of real sighted fire, and being .20 second slower, or point shoot, and take a chance on missing the chest. No issue at 10 ft and less, and not much of one at 15 ft, but it DOES begin to show up at 20 ft or so.