Thanks Stephen. My main opposition (up until now) to doing it via the contact method is that Ralph's book (WBM) and his replies to date in this thread have never pushed it to the point you have which left me with the distinct impression it would be acceptable to carry on with the camera lens in the light path. Perhaps Ralph is assuming we must prevent all other sources of non image light from hitting the lens (the image being the step tablet). And after my learning experience above, I too agree that it is necessary to eliminate all light from around the step tablet and coming in from the sides in the air between the tablet and the lens.

Quote Originally Posted by Stephen Benskin View Post
Ralph's correct in that it's unrealistic to assume there isn't flare in the system, but that doesn't mean it has to be included during the exposure part of the film testing only that it needs to be factored in.
Ralph suggests we deal with flare by using the nomograph in WBM. "In addition, the use of certain equipment, like the type of enlarger or the amount of lens flare, influences the appropriate average gradient and final film speed. The nomograph in book provides an overview of these variables and their influence. The Zone System is designed to control all these variables through the proper exposure and development of the film. This requires adjustment of the manufacturer’s film speed (or ‘box speed’) and development suggestions." (copied from page 1. of the FilmTestEvaluation.pdf he links to in this thread)

Ralph has decided not to push the contact method because of the above approach he takes with the nomograph. He is ignoring the (supposedly small) effect of the flare from the less dense steps in the tablet).

The experiments you conducted Stephen give MUCH larger areas of light which add flare to the image (compared to flare from the few small lighter steps in the tablet). In fact on my Stouffer 31 step wedge each step is only 4mm x about 15mm in size - small compared to the nominal 56x56mm frame size of the negative.

regards
Peter