Can I replace H in the above equation with H-metered from post #2? For a 100 ISO film and a step tablet density of say 0.3, we'd have:

Illuminance at film = (0.08)(10^0.3)

I haven't worked it all through with the proper units but I assume somehow things cancel out and you're left with lux?

~0.16 ?


Edit: Part of what I'm trying to get at here is that while contacting is the best way to plot a curve, most people need a reasonable way to do it without a sensitometer. For example - the current thread in the B&W film forum with the 0.6 gamma etc.