Tri-X Film Testing

When shooting Tri-X, I generally rate the film at 1/2 the published speed, and reduce development appropriately. To increase or decrease contrast, I use times I've figured out over the past few years. I get pretty good results, but I'd like to be a bit more consistent with my results. Since I own Way Beyond Monochrome, I thought I would use Ralph's method for figuring out all this information. Based on my reading of the BTZS, Ralph's method seems to be very similar to the BTZS method for determining film speeds and development times.

So, I went though the testing process - I exposed 5 sheets of Tri-X using my enlarger, made the graphs, used the graphing overlays and ended up with these results:


Dev Time Log Exp Avg Grd
3.5 1.01 0.56
5 0.82 0.58
7 0.64 0.65
10 0.53 0.73
14 0.40 0.80


Note that I was very careful to ensure that the generated graphs were to the correct scale so as to match the overlays supplied with the book.

Development was done using hangers and tanks, HC110 diluted at 1:11 at 20C, 10 seconds agitation each minute.

When I try and graph the above information, I don't have enough information to make any sort of determination for contraction times. My thoughts are that the upswept curve of Tri-X is skewing the results, giving me a higher average gradient that I should really be getting.

I've attached a graph of my results of the 5 tests. I would welcome any comments on the data collected.

What do you mean you dont have times for contraction? Contraction would be your normal time minus one stop, two stops, etc. You results show the different times are having a clear effect on contrast. What is your normal time?

Hi Ken

You're dead right.

Both TXP and HC-110 are designed to give upswept curves.

A higher dilution of HC-110, and reduced agitation, is needed to get a useful N- curve. Or, use Xtol. You'll still get an upswept curve with XTOL: comparing midtone straightlines, Xtol will give a higher shadow density and lower highlight densities than HC-110.

But there isn't any way to make a negative from TXP that will give the full shadows and compressed highlights we usually want from an N- negative.

ON THE OTHER HAND, an HP5 negative does that easily.

.

While the individual graphs do look different, if you take into account the speed points and the point at which the exposed density reached 1.37, the slope of the line (or the average gradient) is very similar for the first two graphs (0.56 and 0.58). There is therefore not enough information here to extend the graph (of dev time vs. avg. gradient) to accurately make a determination of the required development for reduced contrast.

An average gradient of 0.56 works out to something like -0.5 N (I have neither the book or my graphs in front of me). There just isn't enough information to extrapolate to determine other development times.

So, as I mentioned above, I think the avg. gradients for the first few curves are similar because Tri-X has an upswept curve. In other words, I'm not sure how applicable this method of determining the average gradient is for a film which has an upswept curve.

BTW, my normal dev. time for Tri-X is about 6.5 minutes. I use 4.5 minutes for -1 development, and rarely go further than that.

There is always an advantage, and a problem, when we devise a system to describe film's performance.... that's why there have been so many methods in the past !

You can have a TXP neg of a given gradient, but all the curve falls below the slope !
Or, with HP5, or TMY, the average gradient overlays the straight line of the film.

Handy though, having the choices. TXP makes me a much better portraitist than I know how to be !

.

Ken
I agree with df's assessment of TXP. The only thing that comes to mind is that some of your snow and glacier conditions can use good highlight separation.
Some of the best contractions I have from the times I spent out there with the two musketeers were TMX 100 in HC110 1:31 even though I now prefer Xtol.
And you know all this precision will drive BB nuts.

cheers
Mark

Mark Layne said:

Ken
I agree with df's assessment of TXP. The only thing that comes to mind is that some of your snow and glacier conditions can use good highlight separation.
Some of the best contractions I have from the times I spent out there with the two musketeers were TMX 100 in HC110 1:31 even though I now prefer Xtol.

Click to expand...

I wouldn't have thought that TMX would be very good in HC110. I don't use TMax, but it's still good to know.

Mark Layne said:

And you know all this precision will drive BB nuts.

Click to expand...

Shhhhhhhhh!

KenM said:

I wouldn't have thought that TMX would be very good in HC110. I don't use TMax, but it's still good to know.

Shhhhhhhhh!

Click to expand...

I think TMX is better in Xtol for normal use, it wasn't around when I did those.
Incidentally I just developed a sheet of TMX and a sheet of TXP that were forgotten from the '92 trip. The TMX was far less foggy than the TXP so that would be the one to put in the freezer if the worst happens
Mark

Ken, Nice work with the graphs..you should check out the demo version of Phil's Winplotter program.

http://btzs.org/Software/PlotterDemo.htm




Regards,
John

df cardwell said:

But there isn't any way to make a negative from TXP that will give the full shadows and compressed highlights we usually want from an N- negative.

Click to expand...

I get full shadows and compressed highlights with Tri-x and semi-stand processing in Pyrocat 1:1:150 for 36 minutes at 70F with 4 aggitations for 5 sec. each. Your statement may be true otherwise ... with HC110

fhovie said:

I get full shadows and compressed highlights with Tri-x and semi-stand processing in Pyrocat 1:1:150 for 36 minutes at 70F with 4 aggitations for 5 sec. each. Your statement may be true otherwise ... with HC110

Click to expand...

Got a curve ?



Not a challenge, but I'm such a non-technical guy
I need the crutches of graphs !

d

When I get around to it - I'll do a curve - I know the densitometry limits that I measured at SBR of 8 and DR of 1.27, using a calibrated 361T in standard mode for this combo - I haven't yet done a curve - here is a photo though:

(there was a url link here which no longer exists)

The negative has rich tonality and the highlights are intact and within the range of grade 2 paper. The shadows are rich in detail and the tonality is exactly what I wanted when I took this shot.

df cardwell said:

Got a curve ?



Not a challenge, but I'm such a non-technical guy
I need the crutches of graphs !

d

Click to expand...

Ken,

That's one of the strengths and weakens of average gradient. Gamma just measured the straight line portion neglecting the shadows and highlights. The key to average gradient is to measure only the part of the curve that will be utilized in printing (paper's Log exposure range). Kodak's Contrast Index is designed to comes closest to producing similar negatives with a variety of different curve types. If you want, I can go into specifics about the aim values.

The question about your contracted development is that you just don't have a processing time short enough. You can also reduce the dev temp and/or dilute the developer if it appears the dev times will be too short to be practical.