hey guys if you're shooting at an ISO 100 an aperture of f4 and shutterspeed of 1/500 for a correct exposure.. and you cut the lens opening to f5.6, why is it called INCREASING the shutterspeed if you go to 1/250s? Isn't that actually slowing it down? I'm getting caught up in numbers rather than logic. Can you please explain this to me in layman terms? Thanks in advance.