I'm in the process of re-testing my films after an extended absence from Photography. Ironically, I'm still baffled by many of the same questions that haunted me in the earlier years. Reminiscing Fred Picker's "Zone VI Workshop", he would test film/development (for Dmax) on a specific paper AND at a specific column elevation. Is this correct? Or can we safely assume that a negative will print with the same contrast at ANY elevation given that the density values (highs:lows) remain in constant proportion? Thanks for the help!