Slightly off topic...

I do not - and think many doesn't also have access to a densitometer.

So, if I place the camera closely facing a evenly illuminated wall, lens at infinite focus, take a series of shots - normal reading, 1 stop less light, 2 stops less, ...., 4, 4 1/2, 5 stops less, develop normally (at manufacturer's recommended time) and print two adjacent frames at once (including the border area between two frames):

Suppose that between 4 1/2 stops and 5 stops I can notice that 4 /12 is lighter than interframe (film base) and 5 is as dark as interframe, is this 4 1/2 stop less close enought to Zone 1?

Thanks,

Jorge O