"It is simply false that An excellent print cannot be obtained from printing HP5+ developed in Rodinal." (John Elder)(posted 8138 days ago)I didn't say that. I just said you don't get a complete palette of greys and from tonality point I don't recommend to make a large magnification of the neg made that way. Really good 11x14 prints from 35mm neg is challanging especially if you work with fast films processed in Rodinal.
"I think of tonality as the shape of the characteristic curve (contrast in big areas that can be measured with a spotmeter, for e.g.) which determines what kinds of greys you will get from different parts of the scene." (N Dhananjay)
If identical shape of the exposure-density curve can be obtained from two film-developer combinations, do you think the tonality will be identical?
If that question is too hypothetical, then what about if 5x7 and 8x10 prints are made from the same frame of 35mm neg of HP5+ in Rodinal 1+49 and viewed from appropriate distances? Do you consider them to have identical tonality? (assume you can adjust whatever you can in the printing stage with common darkroom techniques)
In my view exposure-density curve is a radically simplified characterization of the film-developer combination disregarding all local properties of the resulting images. Tonality is also affected by more local image qualities including apparent grain and smoothness or "coherence" of each grey level.
It is unrealistic to think a minuscule difference in the curve significantly affects overall tonality, especially because our eyes' ability to discriminate grey levels becomes very poor as the distance separating two grey panels (presented as comparison stimuli) increases. It also becomes poor as the grey panels become smaller. Exposure-density curves are useful measurements, but they cannot predict tonality or many other image qualities by themselves.