T-max, Film Speed, and the Rest

[Nick R.]

I'm trying to see if my methodology used to ascertain speed ratings is correct. Here are a couple of photos that were shot on the same roll, same speed, same dev., obviously, but look quite different.
The details are Tmax3200 shot at 3200 on a Hexar AF in P mode, dev'd in Xtol 1:3 27 min.
By studying the histograms, I believe each shot is one stop underexposed giving me a true film speed of 1600 in this dev. Am I on the right track?

 

[RayPA]

Not sure I understand the question, but it should be the other way around— I think. Shooting at 1600 with 3200 rated film would have overexposed the negative by a stop. (Disclaimer: I have not had coffee yet) 🙂


🙂

 

[Pherdinand]

i think you've misunderstood him, Ray. Go drink that coffee🙂
he says, he used it at its nominal speed although the negs indicate that it should be used at 1600-speed, that is, should be one stop "overexposed" to get the correct exposure.

However, i don't see from the histograms that it would be underexposed. How do you see that? (It is MY fault that i don't see; i am not an expert in this, i wish to learn that's why i ask.)

 

[Pherdinand]

Esp. on the second shot, not sure about the histogram info, but the scanned inverted frame shows lack of details in the HIGHLIGHTS, not the shadows. The black blouse is truly black, though.

 

[jtzordon]

First one looks like it might be a tad underexposed, but the second one looks fine. Of course, I'll throw in the usual "I'm not an expert" disclaimer.

 

[RayPA]

i think you've misunderstood him, Ray. Go drink that coffee🙂
...

good, I was hoping it was my caffeine-defficiency...I heard the coffee maker beep. I'll be back when I've caught up. Thanks for clarifying, Pherdi'

🙂

 

[bmattock]

I'm trying to see if my methodology used to ascertain speed ratings is correct. Here are a couple of photos that were shot on the same roll, same speed, same dev., obviously, but look quite different.
The details are Tmax3200 shot at 3200 on a Hexar AF in P mode, dev'd in Xtol 1:3 27 min.
By studying the histograms, I believe each shot is one stop underexposed giving me a true film speed of 1600 in this dev. Am I on the right track?

Your histogram to me says you're running out of latitude, not over or under exposing. Great position to be in!

My history with histograms (hehehe) is that shot to shot, lots of difference in where the bulk of the data is - having to do with the subject more than the developing. While it is true that severe over or underexposure would leave you throwing away detail, so would improper scanning - you can always rescan, and I sometimes do if I'm not happy with the histogram.

Yes, you have some chop off on the black side - and a bit on the white side. I'd say you've done really well exposure and development-wise.

But I'm a tyro with this. I'll defer to anyone who has more experience than I do, which would be a lot of folks here.

Best Regards,

Bill Mattocks

 

[jlw]

By studying the histograms, I believe each shot is one stop underexposed giving me a true film speed of 1600 in this dev. Am I on the right track?

Your methodology is fine, as long as you remember that what you're determining is the "true speed" of your film/developer/development method/camera metering system/personal metering technique/scanner calibration, not simply of the film/developer combination.

In other words, this info will help you get good exposures for your scan technique once you have enough data points... but anyone else who reads this thread and then says, "Well, I saw online that the true speed of T-Max 3200 in Xtol is only 1600" should get 20 lashes with a wet film leader...

 

[Nick R.]

I should have added that the the hist.'s were of the original tiffs not the jpg's I posted.
I'm trying to use the hist's as a measuring stick. Both graphs butt up against the left or dark edge, hence my opinion that they're underexposed. But, as Pherdinand points out, the lack of details in the highlights suggests overexposure. Now I'm confused.

Nick

 

[rover]

I believe the true ISO of TMax 3200 is actually around 800, so shooting at 1600 or 3200 is a push by one or two stops. The times in the development tables take this into account. I don' t know that the histograms correlate to the film rating at all.

Looking at your two images, they are very different in tones so it should be expected that the histograms are very different.

 

[rover]

In the second shot you don't have a lot of black, just the woman's shirt and coffee pot. You can pull out more detail by dragging the mid tone slider to the left.

I think you will find that the detail is there as the top of the curve isn't being clipped.

 

[Pherdinand]

Strange, in the second shot, the image has alot of bright regions where apparently there are no details, while the histogram shows no highlight data in the extreme right region, say, the last 5%. Are you completely SURE you did not do something like 'auto levels' before converting the originals to the jpeg's you've posted?Could also be that when you've scanned, the highlights were blown out on the neg thus there are regions where no detail is kept, but you(or the scanner) have tried to compensate for this by shifting the whole histogram to the left. This will not increase the detail in the highlights, just make all of it darker a bit. Simply put, if there are five pixels that were all the same brightness, you did not scan them as brightness value 255 but as brightness value of 240 - but they still are of the same brightness.
The other image looks alright, there are no details lost in the shadows, just the contrast is a bit low and the grains are bigger.

 

[Pherdinand]

Here are two versions by simply shifting the midtones as rover suggested. AS you can see, the shadow detalis ARE there; while the highlights (table in the background, napkin in the front) are completely lost. It seems it's true what i thought above, that the scan is simply done by shifting the hist to the darker region but the highlights are in fact gone.

Anyway - remember, a good exposure/scan is important but a really good image does not need perfect exposure (neither perfect sharpness, complete lack of grain, perfect framing etc)

Hope i've helped a bit

 

[Nick R.]

I want to thank everyone for all the ideas.

I don't have the neg's in front of me, but IIRC the one in the mine was extremely thin. That's why I found it hard to believe that it was properely exposed. I'm going to rescan the couple when I get home to see if the highlights are really blown out (I think they are).

I guess the answer to my original question is to find what parts of both shots were reasonably exposed and use that as my guide for future metering.

 

[rover]

Well, I just got home and played a little with your photo Nick.

I made all adjustments as layers,

First layer was Hue/Saturation, I simply desaturated it
Second was the Channel Mixer, Red +56, Green +44 to bring out the skin tones
Then I did a Levels layer, boosted the contrast and shifted the mid tones a little to the dark side.

I think the highlights are still blown out in the napkin and things.

I figured I would give it a shot though.

 

[foon]

like rover said, the actual speed of Tmax3200 is actually 800

http://www.kodak.com/global/en/professional/support/techPubs/f32/f32d.jhtml#1159017 🙂

 

[Toby]

Sorry to be a pedant but the ISO of Tmax 3200 is 1000. Kodak quotes a nominal EI of 800 and pushes of 1600 and 3200. A PDF of the data sheet can be found at http://www.silverprint.co.uk look under 'film' then 'kodak'

 

[Hektor]

1) the film speed varies a bit with dev type and technique, short dev gives lower speed, and long dev gives a bit more speed, but speed varies much less than overall density.

2) you are suffering a bit with not enough latitude in the negs, they are a bit under-exposed and over dev'd. thats normal for t3200 - it's supposed to be used like that.

3) the biggest problem is with the scans, - there is not enough latitude in the scans. The remedy is to dev the film less so that the contrast is low allowing the scanner to capture all the neg has to offer, and then bring the pictorial contrast back up in PS.

4) Of course if you short dev to keep the contrast low for the scanner you'll need to give a bit more exposure 'cause the effective film speed is lower.

5) I'd say set speed to 1000 and give 1/2 or 2/3 suggested dev time, so as to get low contrast negs.

Try this technique and tell us how you get on. Regards John C.

 

[Toby]

I agree with all that John says, however if you are using 3200 in anger low light situation are inherently contrasty and you will want all the speed you can lay your hands on. In Salgado's book Workers he used Tmax for low light. The formula he used (lifted from someone doing work experience at magnum UK was 2000EI Tmax dev diluted 1:6 not 1:4 and I think dev'd for 12-14 minutes (the exact time escapes me) and possibly at 24c . Tmax developer was designed to lift the shadows a bit and I guess 1:6 is to lower contrast. I used this formula in the past and the results were close to TriX.

 

[Nick R.]

I do usually shoot tmax3200 at 1250 but I was shooting in a coal mine had to use all the speed I could get. Funny thing is that I shot the couple at the same speed to finish the roll and the highlights are blown out at least on that scan. This weekend I'll examine the neg under a loupe and see if they're actually there.

I don't want to commit to shooting and dev'ing for scanning as I plan to revisit these and other shots once I set up an enlarger.

Nick