maxim said:
I do have some difficulties sorting out which image is from which film in your gallery, could you point out a few that are on NPS/pro 160
Ah, yes. Oops. Fewer than I thought - in fact none yet*. I'd forgotten when I switched from 100UC to Pro 160S in relation to where I am up to in posting my recent snaps. I had an archival interlude. I'll try to add some Pro 160S in the next day or two.
I'm also not aware of any colour paper that will translate the 14 stops (or 12 or 13 or 15) recorded by a film to print image without fancy work such as contrast masking or flashing or fiendish devilry like digital processing, but I'd like to learn of one. It would look awfully flat with most scenes.
Here are a couple of examples of films printed onto Portra Endura paper - one of the lower contrast papers. First 100UC. This is an example of the difference between the capacity of the film to record a wide scene brightness range, and the translation to a print. The 100UC curve shows an exposure difference (delta log H) of around 3.5 from the toe to the shoulder, or almost 12 stops. In practice it carries on a little above the displayed curve, I find. This is a sensitometric reading, with a real lens the scene brightness range could be higher.
If you print that onto Portra Endura, forgetting about flare, and using a negative density difference of 1.0 as the benchmark, the density range of the paper reflects a log exposure difference of between approx. 1.5 and 1.8, ie 5 to 6 stops. This is just a rough example for comparison purposes. Notice that you can choose which section of the film characteristic curve you use - you are choosing 5 or 6 stops out of a possible 12. Using the toe or the 'shoulder' gives you a slight extra range, though using the toe gets a bit messy.
The next post will be the same curves for Pro 160S. The Pro 160S characteristic curve actually shows less range than the 100UC - delta log H of 3.0 instead of 3.5 (but it also continues a little). However, if you translate the film characteristic onto the print characteristic you get a wider usable exposure difference - up to about 7 stops. Real world scene brightness range translated to the print can be higher than this, of course.
So, with an all-optical process Pro 160S is the lower contrast film. With digital devilry, the 100UC can have a slightly, but not significantly, lower contrast, and a slightly, but not significantly, greater useable ability to record a wide scene brighness range for translation to a print.
Enough for the moment. This example is just an example, it is not a rigorous treatment, and I hope that my simplifications and sloppy words do not cloud the issue too much.
Best,
Helen
PS I've used the blue curve for clarity.
*Two Pro 160S snaps of dead roses now added to 'Garden Notebooks': #15 and #16