Hi, I would like to use my step wedge (trasparent) for getting characteristic curves of the films easily. If I have figured out everything properly, then best way to expose step wedge to the negative is contact printing. That's okay so far... But how do I determine exposure time? If I do contact printing under the enlarger - where do I measure time? And in case of exposure meter, what aperture setting I should give to it? Or if I do contact printing at the dark room with white ceilings using flashes, how do I measure proper flash power for the print? So far I have used step wedge by putting it to the film holder, top of the film like a some kind of sandwich. Then I have exposed 'evenly' lighted surface. This way I get some results, but evenly lighted surface. It seems to be next to impossible. Any tips where to start?