The reason it works for him is camera flare. The Zone System exists in the same reality as tone reproduction. Yes there is some enlarger flare and it also varies depending on the density distribution of the negative. The Callier coefficient for diffusion enlargers compensates for much of it and condenser enlargers more than compensate. Where did you think the numbers from that chart came from. The question isn't about if it works or not but to how it works or should work. How does it all fit together. We do that by first understanding the standard model based on statistical averages. Once that is understood, variations from the norm can then be added.
Originally Posted by Bill Burk
The shorter scale comment of Adams' is meaningless with testing. LER is what defines the paper contrast and not the grade designation. Besides we are discussing theory here. BTW, my paper curves are derived from enlarging the step tablet in a diffusion enlarger in order to incorporate some flare.
2 Quad - Exposure example - Zone - Flare.jpg
In the example, the 1.25 density range from a no flare situation (like a film curve), becomes 1.08 with the addition of one stop flare. Notice the shadow exposure increases from 0.0041 lxs (which is below the aim 0.0064 lxs for a 125 speed film) to 0.0082 lxs which is slightly over it. The metered exposure is at 0.068 as the result of the slight bit of flare at the mid point.
How does this then relate to the print LER?
3 Quad - Exposure example - Zone - Flare.jpg
Check out the print density for Zone V. It's pretty close to 18% gray, yet the reflectance of the subject Zone V is 12%. What are the implications?
Last edited by Stephen Benskin; 05-15-2013 at 08:55 PM. Click to view previous post history.