My explanation was sketchy because that link (and the few books out there) have the detailed explaination, but I'll give a quick overview to help understand.
With your color head just imagine a series like this
Max Yellow, 90Y, 60Y, 30Y, 15Y, 0, 15M, 30M, 60M, 90M, Max M
That will do everything for you.
The tricky part is making them all print with the same exposure. I make them all print grey, but you can base them all on black or white.
You use the step wedge and find out which of the ones above is the 'fastest' (probably leaving out the max yellow and max magenta for now) and which is the 'slowest.' Then you need to figure out how much red (Y&M) to add to each so that they all print the same.
So, once you get your step wedge contact prints you can line them up so the blacks all match, or so the middle gray matches or so the whites all match. You can calculate how far each is off because you know each step of the step wedge is one-half stop.
In my case I know every 30cc of red gives me one stop of neutral density, so I calculated, and added red where needed, based on that. (I then re-checked the step wedge contact print and fine tuned from there).
Last edited by ic-racer; 10-24-2008 at 10:02 PM. Click to view previous post history.