Tri-x 320 or 400?

[brian steinberger]

Along with shooting Tmax100, I would like to adopt a faster film for certain conditions. I'm looking at Tri-x 320 or 400. I've read posts in here about how different the two emulsions are. Can anyone explain. I shoot 4x5, and will shoot 6x6 on 120 as well. I shoot landscape and architechture, and develop in D-76.

[brian steinberger]

Actually I just realized that you can't get Tri-x 400 in sheet film. But I'd still like to know the differences if anyone can help me as far as for 120 roll film. Although it would be nice to shoot the same film for both medium and large format.

[Donald Brewster]

The TXP (320) is designed as a "studio" film, whatever that means. The TX (400) is allegedly different and designed for push processing. Here is what Kodak has to say about the two:

http://www.kodak.com/global/en/professional/support/techPubs/f4017/f4017.jhtml?id=0.1.18.14.23.16.14&lc=en#desc

[Oren Grad]

The key difference is that TX has a shoulder in its characteristic curve; it combines relatively low highlight contrast with good shadow contrast, making it easier to expose for a contrasty scene and maintain detail deep into the shadows. Overall, TX is a very forgiving film, in both exposure and development. TXP, on the other hand, has fairly steep highlight contrast and low shadow contrast, and benefits from controlled lighting in a studio. For my taste it's much harder to get out of TXP the sort of full-information tonal scale I prefer. (Yes, I know that plenty of folks have been using TXP, and earlier TXT, as a general purpose LF film basically forever, and have adapted to its characteristics.)

The two films are so radically different I've always wondered who it was who first came up with the perverse idea of giving the same name to both. I'd dearly love to have the TX emulsion in sheet film formats, but at this point I'm resigned to the fact that it's never going to happen.

[Yong-ran Zhu]

Besides above mentioned characteristics, Tx is the film made Tri X famous. It is good at midtone separation. We usually use it for outdoor photography. The Txp is good at highlight part separation. So it is good for photography with flash.

[Donald Qualls]

Oren, the naming originally was simply a matter of speed. The "X" in the names of Kodak B&W panchro film products designated an approximate multiple of (originally) ASA 25 (which became 50 after the ASA change of 1960). So there was Panatomic-X, ASA 25(50), Plus-X ASA 50(100, later 125), Super Double-X ASA 100(200), and Tri-X ASA 200(400) -- but when the ASA change occurred, the testing method changed as well, and as a result the somewhat different emulsions of TXT vs. TX tested as different speeds (I understand they were the same under the old method), so we have TXT/TXP, in 120 and sheet sizes, now as ISO 320/26 and TX/400TX as ISO 400/27.

FWIW, with a negative material, the situations in which 1/3 stop speed difference is significant are rare.

[Oren Grad]

Donald, that makes sense. So if they hadn't gone off on this "T-Max" nonsense, we might have had Quad-X now instead of TMZ...

FWIW, with a negative material, the situations in which 1/3 stop speed difference is significant are rare

In choosing between TX and TXP, the difference in curve shape is much more important than the 1/3 stop difference in ISO speed.

[Donald Qualls]

"In choosing between TX and TXP, the difference in curve shape is much more important than the 1/3 stop difference in ISO speed."

Exactly. BTW, the "Quad-X" you refer to was actually Royal-X Pan, which (back around 1970, and for a few years either way) was approximately ASA 800 to 1200, I forget exactly -- comparable to 2475 Recording film, but with somewhat finer grain and sold in single cassettes and sheets (I don't recall if it was also available in 120/620). And, perhaps not too surprisingly, also very close to the true speed of TMZ P3200, Delta 3200, and Neopan 1600. It's possible to make much faster films -- there was a Polaroid pack film at one point (for CRT recording, as I recall) that was rated equivalent to ISO 20,000 -- but they don't keep at all well; the faster the film, in general, the faster it will expire from environmental fogging (cosmic rays, if nothing else).

[Oren Grad]

I remember 2475 Recording Film, though I never used Royal-X Pan; I've also had the experience of using ultra-high-speed Polaroid films in the lab to capture oscilloscope traces.

Back when they were new to the market, I did extensive experiments with both TMZ and NP1600 to see how well they would do as "super-TX", or at least a super version of the way I like to use TX - that is, with generous exposure and conservative development to achieve a long tonal scale, but I hoped with an extra stop or so of speed. In practice, I found NP1600 to have such narrow latitude that it didn't take well to that treatment at all, while the grain of TMZ worked against long-scale tonality except in the very smallest enlargements. Oh, well.

To put it back in proper context, these days I spend most of my available photo-time and energy playing with sheet film. I still worry a lot about tonal scale, and though in contact printing overt grain is almost never an issue, one of the surprises when I first started to explore contact printing was that under the right (wrong?) circumstances, it is indeed still possible to produce a really gritty-looking print even with no enlargement at all.

[John Berry ( Roadkill )]

Royal pan was rated at 400. Would quad-X be twice as good as supper-XX?

[Oren Grad]

John, I don't have my oldest Kodak literature handy, but I believe Royal pan was not the same as Royal-X pan.

I don't know whether Quad-X would be twice as good, but it would certainly be twice as X...

[Patti Larsen]

Does anyone have a technical data sheet for the Royal-X Pan film? I'm looking for the spectral response curve.

[M. J. Rossano]

I no longer have the data sheets for Royal-X, but I used it extensively for about a year in the mid 80's in 120 size to document the goings-on in the Engineering Department in the battleship USS Iowa (BB-61), where I served as a division officer. The spectral response, whatever it was, produced results that were indistinguishable from slower speed films of the day.

I really miss this film. Paired with the Linhof Technika IV that I was using, this was an unbeatable combination for producing high-quality results with the atrocious lighting conditions that I encountered. I processed all film in Diafine in my stateroom; an excellent developer for the circumstances where time and temperature were tough to control. Shot at an EI of 1600, I got excellent shadow detail and great tonality.