Ed,(posted 8588 days ago)Actually I agree that the indicator in indicator stop may not be as accurate as we like. The strange thing is there is a similar chemical that does color change at a slightly lower pH, and I have no idea why they don't use it. From chemical suppliers it is about the same price.
For film, I don't worry too much, since plain water works well as stop, and the indicator will change by the time it reaches pH 7.