Quote Originally Posted by PeterB View Post
I don't see why the absolute value of the steepness of the curve in the highlight/shoulder section is the thing to compare. I say this because I will be scaling the ENTIRE curve up or down based on the paper grade I select.
A bigger real difference is easier to get more contrast from, especially if you need to burn in or are fighting against the paper's curve to get that detail printed.

Quote Originally Posted by PeterB View Post
As you mentioned I should be comparing the middle curve to one below it, but the effect is too small to observe with the limited data present in those curves.
The two ideas above are related and the effect is too small to see in real life too. The point is that there is no gain to be had. It's the equivalent of moving your wallet from your left pocket to the right pocket, it doesn't change how much money is in your wallet.

One reason that I almost never adjust film development/change the contrast rate is that my normal film development (regardless of my camera exposure placement) sets me up to get the best prints from my paper.

I only move away from my normal paper grade as a last resort. Moving away from my normal print grade compromises the print because the the shape of the paper curve starts changing too. That doesn't mean I won't change paper grade, just that I use it sparingly.

Quote Originally Posted by PeterB View Post
As I noted above, Ilford have not included any should information in their HP5 characteristic curve so we cannot conclude anything only assume. Even if its shoulder characteristics were different, I would be surprised if the general shape didn't generally follow that shown with TRI-X.
You are right that with the info at hand we are guessing a bit, but just because Tri-X 400 shoulders a certain way doesn't mean HP-5 will follow suit. Flip a couple pages from where you got your graph and look at TXP/Tri-X 320 it doesn't shoulder like Tri-X 400 and it is even made by Kodak.

Quote Originally Posted by PeterB View Post
Very informative thank you. At least I know not to reduce my agitation lest I further compress my highlights !

Time now to walk the dogs and get to bed.

regards
Peter
Exactly, that is why in this particular situation the compensating development schemes and developers aren't the right answer.

A little extra agitation would mitigate a good bit of the process variables that you are worried about.

Sleep well.