Richard Henry’s oft quoted study of the variables in making black and white photographs was meant to test common, and widely held opinions among darkroom practioners
It is remarkably different in content, intent, approach and result to the Lustrum Press “Darkroom” set of books. I direct people to those over this book, and strongly advise against the Ansel Adam’s series. I bet you already own Ansel’s books and google brought you hear thinking you’d get a free look. Sorry, just some summary info, although I have mentioned his conclusions throughout posts and I do use his results to inform my process.
In Brief: Everything You Hear on The Forums is Useless.
The magic bullets: Dektol (1:1); D-76 (1:1)
My magic bullet: make more pictures, even if they’r digital. Read books that don’t have charts and formulas — this assumes you are after what is sold by the workshop world as “vision.” I don’t know if you will get vision. I don’t know if you’re capable of making pictures that X or even Why.
I am certain that the longer it takes you to get beyond the methods books and message boards the less likely you will reach satisfaction in image making or photography.