Speed increasing developer

Barney

Barney

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Wayne
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I have been reading FDCB,

A little bit of knowledge is a dangerous thing, I am on my second read as there is so much information to absorb and digest, I will probably read a third time as its almost certain I have failed to appreciate tons of stuff.

I am looking for clarification regarding Speed increasing Developers in general and what they achieve. Related to a recent thread on Pushing and pulling, does the speed increase manifest itself as an effective reduction in box ISO?
 
You can never increase or reduce the ISO rating of a film, which is calculated using a specified set of procedures documented in an ISO standard.

When we develop using a speed other than the box speed, it is properly referred to as an Exposure Index, or EI. The EI is the rating you have determined for your particular combination of film and developer, development time, temperature, and agitation method.

A speed increasing developer would aim to INCREASE your EI, not reduce it.

Having said all that, and I own both the Film Developing Cookbook and the Darkroom Cookbook, I only use one developer for all films and EI ratings.
 
Geoffrey Crawley (I think it was) who developed (pun or not, as you choose) several developers including Acutol, said that he had never encountered any speed increase above half a stop.

Acutol is the only developer I've ever used that gave a different noticeable to me result than every other developer I've used. Which isn't many - in over 60 years years developing films, I've used Unitol, Acutol, Acutol-s, Promicrol, Rodinal and Johnson's Univeral developer. And of those, only Unitol , Acutol and Rodinal have been more than one bottle.
 
I appreciate that the pair of you have vast experience producing negatives and fantastic prints, but with the advent of modern emulsions and ever improving formulae of existing films has it never piqued your interest if another film/developer combo would give more precise tonal ranges and/or contrasts.

I know its hard to change when your set in your ways, but variety is reputedly the spice of life.
 
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