A method of exposing a radiation-sensitive medium through a mask and using an imaging system having a given depth of focus to control for pattern dependent distortion. The steps comprise: providing the radiation-sensitive medium within the depth of focus of the imaging system; providing radiation to the radiation-sensitive medium through the mask; providing the radiation-sensitive medium fully outside the depth of focus of the imaging system; and providing radiation to the radiation-sensitive medium through the mask. Corrections are automatically made by providing the radiation-sensitive medium fully outside the depth of focus of the imaging system, since in that regime the mask operates as a gray-scale mask, with the amount of light passing through any region of the mask dependent on the transmission of the masking pattern in that region.