In 120 roll film, I can get either standard Tri-X or "Professional" Tri-X. I noticed that the Pro Version is rated slightly slower at 320 than 400.

But what really is the difference between the two? Or are they really the same emulsion? Like Astia is Sensia II.

-- Sol Campbell (solcam31@hotmail.com), September 30, 2000

Answers

No, they are different. TriX Pro is set up for studio use. It has a different density curve and, I believe, it lacks the anti-halation coating of the other TriX.

-- Don Karon (kc6d@arrl.net), September 30, 2000.

That is a shame. I was hoping to get some 220 rolls too. Only the Pro version is available for that format.

Do you have any experience of the Pro version? Is it quite similar?

What is an anti-halation coating?

Thanks!

-- Sol Campbell (solcam31@hotmail.com), September 30, 2000.

Although I haven't paid much attention to Tri-X, I believe these are the differences:

TXP is a short-toe film with a fairly straight-line characteristic curve; this means it has higher shadow contrast, pretty much no underexposure latitude, and higher highlight contrast. I believe it also has a retouching surface on the base side, although that may be of no interest.

TX is a moderate-toe film and has a shoulder in the high end of the curve; this means lower shadow contrast but some underexposure latitude and lower highlight contrast.

They are definitely not the same emulsions.

Which film works best for you will in part be determined by what paper you're printing on; TXP may print better on a long-toe paper such as Ilford MG IV RC while TX may give muddy highlights, while otoh TX may print better on a shorter-toe paper such as Agfa MCP while TXP may have hard-to-print highlights on that paper.

-- John Hicks (jbh@magicnet.net), September 30, 2000.

As far as I understand it: Antihalation coatings suppress reflections of light that scatters in the film itself.

-- Don Karon (kc6d@arrl.net), October 01, 2000.

Yes, these are two completely different emulsions. Why Kodak saw fit to call both Tri-X, only they know. In my opinion, this is misleading and dishonest. TXP has a real speed of 320, like TMY; TMY is a better film, less general fog, straighter curve, less grain. TX is rated at 400, but will not get above 250. Even then, it shoulders rather severly beginning at Zone VII. If you are looking for a GENUINE 400 speed film, one that is the SAME EMULSION in all formats, use Ilford HP-5+. This film has a moderately short toe and is ruler flat from Zone II past Zone IX! It stains beautifully in PMK and produces superb prints. Generally, the best B&W film is made by Ilford. You can't go wrong with any of them. Just beware; Delta 400 is actually 250.

-- Michael D Fraser (mdfraser@earthlink.net), October 01, 2000.

Re: Tri-X speed. It is indeed ei 250 in a fine grain developer like microdol-x but it is closer to 320 in d-76. As far as Ilford vs Kodak, I prefer Ilford btw I'm getting an ei of 320 with delta 400 as well. Perhaps it's my equipment.AT any rate before I started using delta 400, tri-x was my film.

-- Robert Orofino (rorofino@iopener.net), October 01, 2000.

I believe, based on Kodak litterature and use, that *some* of John Hicks information is wrong. TXP 320 has a longer toe than TX 400. TX 400 has therefore a larber separation of shadows than TX 320 has, but (as John says) the TX 320 has a better highlight separation because it lacks the shoulder that TX 400 has (the shoulder compresses the highlight values).

-- Peter Olsson (peter.olsson@lulebo.se), October 06, 2000.

> TXP 320 has a longer toe than TX 400.

You're probably right; I was just running on vague recollection.

-- John Hicks (jbh@magicnet.net), October 06, 2000.

I have used both and the differance is vary slight. Just pick one type of film that gives the grain quality you like and is the easiest for you to work. Stick with the same film and learn what it can do for you. I think that your printing skill should be able to make up for highlight seperation and shadow contrast.

-- Paul Baucom (Tri_x35@hotmail.com), January 14, 2001.