The lee sw150 neutral density nd grad medium filter set contains three 150 x 170mm graduated resin filters 03 06 and 09 that enable the photographer to adjust exposure by 1 2 and 3 stops over part of the photograph without affecting the colour balance these nd grads feature a medium transition from dark to light and are ideal for use when elements of the scene protrude into the sky be that the rooftops of buildings or the peaks of mountains the nature of the transition between coa