To get the true speed of a film, draw a straight line extended out from the B+F to infinity. This is done using the H&D curve. Then, note the deviation point of that H&D curve from the straight line. This is the inflection point of the emulsion and is the maximum point at which this emulsion can register an image. It is called "threshold speed".

Translate that into speed using standard methods and you get the max speed of that product.

Now, create a developer that swings the curve on that single point and you have a developer than can approach that speed point. At this time, the maximum threshold speed ever achieved is 25,000. These materials were never sold.

Unless the MSDS is published, it will remain to be seen if this new developer works well.

PE