You can establish the correct amount to increase development times by similar N+1 and N+2 tests. You will often find that the maker's recommended time is about right for N +1. Again true film speeds may need fine-tuning with around a half stop reduction in exposure, i.e. a 50% increase in film speed from the figure you already ascertained by testing for a normal subject brightness range.

TAKING CONTROL

It is encouraging for newcomers to the use of the zone system of exposure and development control that it very soon operates as an unconscious and rapid process not of setting camera controls, but of seeing the image required in its correct tones of grey. It's a freeing of vision, not a pedantic technical exercise. Actually, it is incorrect to talk of a photographer using or not using the zone system. Quite a few 'serious' photographers have told me that they don't choose to get involved in all this technical hang up - their interest is only in taking the picture. To my mind, that's like chefs with all the ingredients before them saying they can't be bothered with all this cookery business - "my interest is only in the final meal". Usually with photographers it also boils down to "can't be bothered". These are often the self same photographers who use that dreadful phrase, "it didn't come out". Encouraged by many amateur photographic magazines, they bracket exposures above and below the indicated averaged meter reading. This is not only music to the ears of film manufacturers, it confirms the photographer as a guesser. It relegates the creative process to some form of gambling: if the tonal range in the image is not too wide, one of the exposures may achieve the desired result. Whether the imagined picture arrives is purely luck of the draw. This is sad because the photographer, in attempting to visualise the end result, is apparently intent on artistic achievement, but is at the same time depriving himself of the surest available means of realising the vision. Let me be clear. I believe a photographer works with the zone system of exposure whether he or she likes it or not, simply because the zones are the immutable laws of sensitometry. It is, quite simply, what happens regardless when an exposure is made. The only questions are: does the particular photographer understand what is happening; does the photographer know how to control it; does the photographer know how far that control extends; and can the photographer pre- visualise the image required and achievable? If the answer is "no" to any of these questions, then the whole process becomes a lottery with the occasional lucky strike spaced out with the usual massive majority of frustrating failures. Indeed, much of the satisfaction is removed from the odd success because the photographer didn't really cause it. So does the use of the zone system guarantee success, if only in terms of a technically good negative? Unfortunately not. We are human and make mistakes. My list of embarrassing failures would rival anyone's. Though I never say "it didn't come out", I guess my expletives at the sight of a nearly black or virtually transparent negative emerging from the fix have grown more picturesque over the years. All I will say is that whenever 1 have forgotten to allow for a filter factor, forgotten to set the correct film speed on my meter, forgotten to withdraw the dark slide, or failed in many similar ways, it will always have been with a magic but unrepeatable picture, or one that had meant hiking miles over tough terrain to the point of exhaustion.