I am building a homemade f-stop timer. I think I've figured out the basics but one question I have is whether the steps between f-stops should be in tenths, twelfths or even sixteenths. It seems that tenths may be too coarse since some say that prints that differ in exposure by a twelfth stop are noticeably different when placed side by side. Then what about sixteenths? Is that overkill? Thanks.