The three B&W films are intended to give a range of practical speeds, from 640 to 12,500 and beyond. Their 'true speed' cannot be measured by conventional means, as a BTZS practitioner might determine the speed of a film for shooting LF. Judge them by midtones, and a practical usable scale. My personal standards are far lower than those of a Fine Artist, so I'm delighted by these films.
At 12,500 the films give superb midtones at the expense of a infinite range of details at Zone III. Great trade-off.
My experience with TMZ goes back to it's pre-introduction when I was fortunate to have some of the mystery film in a plain yellow box. The guy from Kodak said to shoot it between 1600 and 12,500, soup it in D76, and try a roll before gambling the mortgage.
Over the next 6 months, I shot a thousand rolls of the stuff, exposed between 640 and 25,000 and got great results. The working practice was, and is, shoot it at whatever speed is needed for the shot and develop accordingly. I haven't looked back. It was a whole new world from my previous 18 years shooting Tri X at 1600 and hoping for the best. You have NO IDEA !
I use XTOL now, and don't do much above 3200 anymore ( leading a duller life, I guess ) but the film becomes anything I need it to be. Soft, foggy, smoky, rich and glowy at 640, pointilistic and razor sharp at 6400, reliable and practical at 25,000. I grew up with Royal X and Recording film: they were a grotesque joke compared to TMZ.
I've used Fuji and Ilford enough to confirm they pretty much work the same way, and that if I ironed them out as I had TMZ, they'd be equally dependable.
True Speed ? Decide what you want the 3200 films to do for you, and develop your technique to suit 'em. Don't treat them like some ISO 25 film, get to know them and go have some fun.
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