Thanks for an interesting and informative thread.
Still being a relative novice, I must try to incorporate some of these ideas into my process. I believe that I understand the basis of "expose for shadows and develop for the highlights" and I like the idea of a simple system. Mike Johnston's "Not much of a system system" therefore has great appeal and was, I initially thought, an easy system to use, or at least must be far better than making no allowances for differing contrast scenes.
I can understand the effect of changes made to the IE and appropriate changes in development times, along the lines of the example he gives for his process using Tri-X:
For a scene of normal contrast EI.200 at "std" development time.
For a scene of low contrast use EI.400 and increase dev time by 30% over std.
For a scene of high contrast use EI.100 and decrease dev time by 15% from std.
This is good so far, but I have been thrown into confusion by a later suggestion that, on a roll used over varying scene contrasts, that one should use a middle dev time and stick to the suggested changes in EI.
This is very confusing for me, perhaps I haven't grasped this at all......
If I were to do this, I might have a new "standard" dev time (from an average of the above times) and expose thus:
For a scene of normal contrast EI.200.
For a scene of low contrast use EI.400.
For a scene of high contrast use EI.100.
Develop at "std" time
But hasn't this reversed the changes in contrast? I mean, if I were to change from EI200 to EI400 for a contrasty scene and then dev for the same time that I would have done for the EI200 (normal) scene, then I have effectively reduced the dev time for "normal development for that speed" and so reduced the contrast?
Regards, Dave