Tonal range of Chromogenics compared to trad. B&Wgreenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I've been doing some comparisons between the Kodak Chromogenic T-400 CN and traditional films like T-Max 400 and HP5+. At first all I saw was how much finer the grain structure is in the Chromogenic. But now I'm starting to notice that maybe the chromogenic doesn't have quite the subtle tonal range of HP5+. It also seems that colors like the lips and eyes seem to come out much darker. It almost looks like the kids are wearing lipstick. Bright blue eyes look like brown eyes and brown eyes turn into black pits. Anyone know of comparison info on tonal comparisons between the two film types.
-- Jay Johnson (firstname.lastname@example.org), January 28, 2000
In my experience, T400CN yields the same "extended-red look" as Tech Pan in the rendering of colors. I've displayed prints from Tech Pan and T400CN side-by-side and aside from the differences in grain structure and contrast (minimized in printing), the rendering was similar enough not to jar my sensibilities.
Unfortunately, my experience with both films is that lips tend to be de-emphasized (just checked a bridal portrait to make sure). Also, the tonal scale on T400CN is much longer than any other film I've used. It does look very different compared to traditional films.
Your print-tone comments sound as if the T400CN you shot was printed at higher than normal contrast.
-- John O'Connell (email@example.com), January 29, 2000.
Thanks for your experience and technical background info. I'm not a professional photographer so I had to look up some background info on tone curves and what a "long" tone curve means in a print. I think I've got it.
I also think a friend clued me in that the Tech Pan films you traditionally use have a sharper, punchier, look to them than the Tri- X or HP5+ films I was using. I'm starting to think that the Chromogenics are more similar to the Pan films (sharper, more clearly defined tonal changes, etc.) than they are the traditional film types. I've looked at some photos taken by others and am gaining confidence in this theory. You seem to support this line of thought.
I was wondering though, when you mention "extended-red look" are you implying the film responds to reds in a way that creates a dark neg. and therefore a light print for red tones?
You may be right too in regard to the print contrast. My printing was done by a commercial lab so I don't know how the contrast range was determined. It's very possible the HP5+ prints were done by one person who thought a softer look was better for that subject (littler girl in frilly white dress and hat) and someone else, months later, did the Chromogenic print and liked a punchier, higher contrast look.
I must admit, both looks have merits. I'm not sure which I prefer.
Thanks again for your earlier advice.
-- Jay Johnson (firstname.lastname@example.org), February 03, 2000.
You are mistaking color response for tonal range. Tonal range is the amount of light difference that the film can display from black to white. And how fine of steps of light difference you can see (not really tonal range, effects tonal preception).
Color response has to do with how the film turns various colors and intensities of those colors into shades of gray. This will effect how things like lips with show as darker or lighter. B&W film typically responds to blue more than red. So blues tend to be whiter and reds darker on the B&W image (print). With extended red sensitivity, reds go lighter.
So it sounds like T400CN has a little less red sensitivity than TMax 400 or HP5+. If so a little filtering can bring it back to the way you prefer.
-- Terry Carraway (TCarraway@compuserve.com), February 04, 2000.
This is a little off the subject, but I've been told that with XP-2 the image contrast can be shifted by exposing at different ISO. For example, if there is an extremely contrasty subject in bright sunlight, by exposing at ISO 200, it's "gamma" is shifted far enough down the H&D curve to be the equivalent of N-1 development. Conversely, exposure at ISO 800 will shift a flat subject up the curve to the equivalent of N+1 development. Any truth or partial truth to this?
-- Bill Mitchell (email@example.com), February 04, 2000.
Yes, XP2 does change contrast/tonal range in the way described above. I suspect T400CN does too. XP2 has a very, very long scale and you can change the contrast by changing the exposure. The more light it gets the more contrast and the finer "grain". The less exposure the softer it gets and the "grain" in the dark range of the print gets larger. Of course it responds to filtering too. And you can do this all on the same roll because the process stays the same. I use it from 200 to 1600! It looks VERY different at various exposures. Test and see for yourself.
-- Henry Ambrose (firstname.lastname@example.org), March 22, 2000.
HP5+ shows a fairly straight curve shape through 15 stops (the limit of my testing) while T400CN has a very strong shoulder.
So...HP5+ definitely has a longer tonal range in that it doesn't drastically compress the highlights.
Otoh, more highlight detail would be rendered in a print from T400CN, although at low contrast.
-- John Hicks (email@example.com), March 23, 2000.