View Full Version : Zone system testing method
Ray J Wallin
I just bought my first 4x5 camera. I have been using the zone system with my 35 mm for 5 years now and am very familiar with it. I wanted to establish my perso nal ASA for Tmax 100 for the 4x5. I bought the film, loaded it, took a high con trast set of a few pictures of the downtown skyline. I placed the shade of a da rk building that still contained texture on zone III. I took a picture and brac keted as well 1/2 and one stop. I developed the film in TmaxRS and an unexposed sheet as well. I went into the darkroom and exposed a test strip with the unexposed sheet to fi nd my 'standard printing time'. When I expose the negative of downtown, the pri nt is completely white. I am now confused. I will repeat the process, but I am sure I did everything right. What would you do?
Firstly, T-max can be a real headache. It's not a film for beginners (and I shou ld add that I'm still coming to grips with it). The reason is becasue its maximu m density is over 3.0; most films taper off at a maximum density of around 2.0, but T-max keeps on going. I don't know if you're familiar with characteristic cu rves and logarithmic density units, but that means that a T-max negative can be 10 times denser than an ordinary negative!
So my guess is you've overdeveloped your negative, that's why its coming out fla t white. With a film like Tri-X that has a sloping shoulder the highlights would have blocked and the negative wouldn't have been too dense. But because of the long scale on T-max, if you overexpose or overdevelop it you wind up with a nega tive that's unprintable. (Let me know if you're not familiar with terms like sho ulder). So if I were you I'd halve your development time and start again.
Also, are you using a prewash? I was using a prewash with Delta 100 and I just d iscovered you're not supposed to. It was causing me to overdevelop my negatives.
Finally, you don't use the 'standard printing time' test for determining your AS A; that's for the development time. You determine your ASA by shooting bracketed frames of a dark surface you place on Zone I; the one that produces a density o f 0.10 above film base is the correct ASA.
Let me know how you go.
I don't mean this answer to be flippant or sarcastic but I would buy or check ou t of a library any book that contains detailed instructions on how to perform th e film speed tests The method you used seems very rudimentary. Any number of pho tography books contain such instructions. A few that come to mind are Ansel Ada ms' book "The Negative," Fred Picker's book (the name of which I forget but he o nly wrote one), or "The Zone System Craft Book" by John Charles Woods. There are many others but these are three I am familiar with.
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