Good amount of information here, but I need to add a note of caution about Efke 25. Donald has mentioned Kodak's suggestion about reducing development, while Steve has mentioned a need for increased contrast in much of his work. Aren't we are talking about a seemingly similar situation with respect to reciprocity?
I don't have a fraction of the background in Donald's testing, equipment or experience, and I certainly don't come close to what Steve has been able to accomplish with his methodology, so please take these observations with a large pinch of salt. My only experience comes from working with Efke 25 for two years. Donald's statement about Kodak is based very specifically on Tri-x, a film which can be developed to expand about a stop and a half. Steve has been working with J&C's 200, another film which is not capable of large amounts of plus development, in my understanding. The wild card here is Efke 25. It is a slow film which builds contrast beyond most other film's capabilities. I think Donald has mentioned in a previous thread about it being capable of building more contrast than is necessary for most, if not all, current photographic materials used today. He had mentioned a number, but for the life of me I can not remember it. This includes silver printing, as well as alternative process materials. My point here is that we are at times in uncharted territory with respect to differing films, contrast levels of light and exposure. Finally the film's tendencies with respect to development are another variable.
Perhaps Donald can help us out with a few numbers, by way of an example, which would compare Efke 25's potential contrast scale to that of Tri-x, since I can't. I think this might be helpful to those of us without a background in sensitomitry and the numbers which mean so much to various papers. Basically, Efke 25 can build contrast in flat light that other films can't come close to matching. I think in some respects here, we are comparing apples and oranges when we talk about different films and how they react to light and development. This is the wonderful thing about film and light. Just when we think we have figured it out, a new situation appears and we have to think very hard about how we can deal with it to make a good print. tim