Q What is the highest film speed that renders a fully detailed Zone III and a Zone II that is black with texture

A: Film manufacturers must necessarily use consistent and scientifically objective criteria for determining the ratings of their films. Photographers, on the other hand, need

ASA ratings that they can count on to give them the amount of shadow detail they visualize when considering a given subject. This is a very subjective evaluation and will vary somewhat depending on the kind of work you do and other variables such as the paper grades you like, and so on.

The standard we have used for these tests is conservative and intended to give you as much exposure latitude as possible, the highest ASA, and good shadow detail in Zone III.

Our goals were to produce negatives that would generally be easy to print on a normal grade of paper (grade 2). From this starting point you can begin developing your own personal standards.

A fundamental principle that all photographers should understand is that the effective speed of a given film varies depending on the developer used. Notice for example that 400TMax is rated as ASA 200 when developed in Ilford Perceptol, and ASA 400 when processed in Edwal FG-7 with a 9 percent solution of sodium sulfite.

What this demonstrates is that it's important to know as much as possible about how the characteristics of different developers and films interact before deciding on a combination to use as your standard. See Appendices E and G for more information on this subject.

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