The density change in the film will not be the same as the density change in exposure due to the gamma of the film. If your step wedge changes .3 density units from one gray patch to another, then the film density will change by the change in exposure (the step wedge change) multiplied by the gamma of the film. For example, if the gamma if the film is .5, then the film density change would be .3 x .5 or .15. So a change of exposure of .3 density units (one stop of exposure) results in a change of density on the film of .15 units. The actual gamma will depend on the film used, development time, and curve shape.
Last edited by RPC; 05-02-2013 at 12:51 PM. Click to view previous post history.