Testing film? Using a densitometer?

[stawastawa]

Trying to quantify a lot of variables at once can be problematic.

Yup!

[jvo]

Kodak had a nice tip for evaluating your negatives.

Place your negative over top of a newspaper. If you can just read the type through the highlight area, and there is detail in you shadow area you pretty much have a good negative.

After 40 years of printing for others I still find this to be good advice.

Bob

whatsa newspaper?

[Pere Casals]

It's the character of the shadows that counts, not just some hypothetical end zone goal. Different types of film differ in this respect, and all of this is tied to your
particular aesthetic objectives. I think in terms of the shape of the toe of the film. In this respect, both ISO standards and the Zone System can be misleading. If you do use a densitometer to evaluate your film using a predictable step tablet, you'll want to pay attention to how evenly the reproduced steps are space, density-wise, and how far along the scale. Basic curve plotting skills are important. But there is often a difference between lab performance of these films and how they respond in the real world under more complex variables. Otherwise, unless you just happen to enjoy the technical side of this, all the math and so forth if apt to be a wild goose chase unless you understand what a goose looks like first. In other words, you might be better off just shooting and printing, shooting and printing, until it makes sense. Trying to quantify a lot of variables at once can be problematic.

I agree that the character of the shadows are very important in the final print, anyway there are two ways to work the shadow's character, this is how shadow's range is compressed.


Option 1:

One way is to compress the shadows placing them in the toe of the negative.


Option 2:

The other way is to place the shadows in the linear area of the negative but placing them in the shoulder of the paper. Similar compression can be achieved.



At the end Option 2 gives more choices when printing the shadows. But this has also drawback with contrasty scenes, as placing shadows in the linear area of the curve also takes more dynamic range of the negative, because with "Option 2" strong highlights can have a lot of density on the negative, can be more difficult to print, and perhaps can even be lost.

Well, at least this is the conclussion I've arrived... but I'm still fighting to master those skills. Doing that in Photoshop it's very straight, doing the same in the darkroom requires a true photographer there. Worth to learn it.

[Bill Burk]

The way I understand it, you get an S-curve with paper... and you get a hockey stick or J-curve with the film. Shadows are pleasingly compressed when you use a little bit of the optional J in the toe of the film as well as the given S of the paper. If you shoot up on the straight line, you only get the S-curve of paper (only the shoulder compression on the print). You also get another "J" superimposed by the action of flare.

I also believe the film and paper curves are able to be controlled by the manufacturer, have been specifically designed for the purpose, and that the shapes of both curves were designed so that they work together this way. You are expected to use some of the toe for your shadows. Those who shoot up on the straight line are shooting off their... well they're shooting off a lot.

So why do I still shoot up on the straight line? Because the difference, though it exists and can be demonstrated and measured, is not yet significant to me. Maybe one day I'll be sensitive enough to want to use the toe. But for now I'm happy with the look of my prints that I get when I use the straight line.

I really like the demonstration that Ralph Lambrecht put in "Way Beyond Monochrome" because it shows the delicate differences in the shadows in a way you can really talk about. The bench under the window looks better when shot on the toe when compared to the similar best print he could make when he used the straight line.

Bottom line: If you see something you like, try it both your old way and the way the photographer did it the way you liked. If the photographer's tip worked to give you something different than you would have otherwise gotten, and you like it... you've just added another trick to keep up your sleeve.

[neil poulsen]

I'll try to address your question. A few things:

1) Regarding contrast/development times and film speed, the ISO speed methodology is rooted in print quality studies. The studies found that rather than basing film speed on a fixed density target, it is the contrast of the shadows in relation to overall contrast that should determine film speed. ISO is a "shorthand" for this methodology. Ultimately what we care about is how the shadows separate in relation to total contrast. This seems obvious, but note the Zone System doesn't do that. It always locates a fixed density for the speed point whether you are developing + or -. The important point here is that the speed underlying an ISO rating doesn't move around nearly as much as a Zone System EI when the film is developed to different contrasts. I think that was what you were asking. . . .

That's interesting . . . of which paper?

How do we know that the film being purchased by a given photographer will ever be used on that paper? (Or papers?) In this case, does the film speed not become dependent on the paper (or papers) selected for the print studies? I may be over simplifying a bit, especially since I'm not familiar with the methodology involved in the standard. But personally, I would prefer that film speed determination be independent of a given, or a group of papers. There are so many different papers (and different behaving papers) that are available, even now.

It may sound like I'm attaching the ANSI/ISO standard, but I'm really not. Perhaps I'm more playing devil's advocate.

As to my own testing, it's true that the Zone System film speed test doesn't rely on print studies directly. Recall that it determines the film speed that yields a developed Zone I exposed sheet of film that prints 0.01 density units above film base plus fog. Then during subsequent (at least my) Zone System testing, maximum paper black (for the paper that I actually use) is determined by printing through an unexposed, but developed (at the developer's recommended time and temperature) sheet of film. That is, it's determined by printing through a film base plus fog sheet of film. Once I determine this black by varying exposure time on my enlarger, I determine N development by seeing which development time gives me a Zone VIII that I like, when printed on (my selected) paper at the enlarger exposure time that yields maximum black.

So while Zone System film speed tests themselves are independent of print quality studies (which I tend to prefer), Zone System methodology itself does come back to print results on the paper that is actually used by the photographer.

To address a possible hanging question, how did the value "0.01" above film base plus fog originally get chosen? I suspect that it was the minimum value that would actually work in practice. Of course, to determine what "works in practice", would need to, in some measure, be based on print studies.

With all this discussion, I fear that we're getting beyond the OP's original question. But, the discussion has been interesting, none the less.

[Pere Casals]

The way I understand it, you get an S-curve with paper... and you get a hockey stick or J-curve with the film. Shadows are pleasingly compressed when you use a little bit of the optional J in the toe of the film as well as the given S of the paper. If you shoot up on the straight line, you only get the S-curve of paper (only the shoulder compression on the print). You also get another "J" superimposed by the action of flare.

I also believe the film and paper curves are able to be controlled by the manufacturer, have been specifically designed for the purpose, and that the shapes of both curves were designed so that they work together this way. You are expected to use some of the toe for your shadows. Those who shoot up on the straight line are shooting off their... well they're shooting off a lot.

So why do I still shoot up on the straight line? Because the difference, though it exists and can be demonstrated and measured, is not yet significant to me. Maybe one day I'll be sensitive enough to want to use the toe. But for now I'm happy with the look of my prints that I get when I use the straight line.

I really like the demonstration that Ralph Lambrecht put in "Way Beyond Monochrome" because it shows the delicate differences in the shadows in a way you can really talk about. The bench under the window looks better when shot on the toe when compared to the similar best print he could make when he used the straight line.

Bottom line: If you see something you like, try it both your old way and the way the photographer did it the way you liked. If the photographer's tip worked to give you something different than you would have otherwise gotten, and you like it... you've just added another trick to keep up your sleeve.

Bill, thanks for this explanation.

After you pointed it I've just read the preface of that book:

"The book will take the reader on a journey, which will transform ‘trial and error’ into confidence and the final print into something special."

I'm to read that book.

I guess that combination of S and J shapes of paper and film come from refinements that evolved upon market acceptation. This is an imaging culture that took more than a century of artistic-industrial feedback.

Also from what you point, I'll make tests by bracketing, thus placing the shadows a bit in the toe and not, and later looking how both negatives can be worked in the darkroom.

Thanks again.

[Drew Wiley]

Different curve shapes in film were engineered for different applications, though quite a few black and white films land somewhere in the middle, for versatility.
In the old days you had an "all toe" film, Plus-X Pan, marketed to studios with controlled lighting and a lot of potential high-key applications, like Caucasian brides
in white wardrobes. Then you had a "true straight line" film (again, a bit of hyperbole, but descriptive nonetheless), namely, Super-XX, which would handle extreme lighting ranges with consistent gradation. This is a very different thing from merely "minus" or "compensating" development, which might successfully
squeeze the ends together, but at the expense of midtone texture or microtonality. Then there was a popular film with intermediate curve characteristics, Tri-X.
Of course, all kinds of other films were on the market; but these are the ones a Photography School student would be routinely expected to understand. Today
about the closest thing to Plus-X would be Delta 100, to Super-XX, TMax400 (though Fomapan 200 fits the straight-line niche better, but not in a practical sense),
and we've got all kinds of popular mid-application films, like FP4. I might choose a completely different film on a rainy or foggy day than in high contrast settings, due to the nature of the curve. For example, the pronounced S-curve of Pan F can do wonderful things in soft lighting, but be hell to print given a high
contrast subject. It has relatively little usable range, maybe just Zone III to VII. But a straight-line film might give you up to twelve full stops of range. Most
films are somewhere in between, and a good example of that category available in many formats would be FP4, which would also be an excellent film to learn
the basics on.

[Jerry Bodine]

...As to my own testing, it's true that the Zone System film speed test doesn't rely on print studies directly. Recall that it determines the film speed that yields a developed Zone I exposed sheet of film that prints 0.01 density units above film base plus fog...

Neil-
I think your recollection may be a bit fuzzy. ZS film speed is base on 0.10 density above fb+fog (not 0.01). Just a typo maybe?

[Drew Wiley]

If that's true, it simply indicates a kind of generic approach that is potentially misleading. A few films start showing distinct gradation merely .05 above fbf, most
need around .15, while some need up to .30. So in most cases you're dealing with the degree of the slope and not discrete zones. In other words, it's all relative,
both with respect to how many zones the world is divided into, and what the nature and reproduction characteristics of those zones actually are, especially when
you're talking about either the toe or shoulder to the film. I'm not discouraging the exercise itself, but merely indicating how relative everything is, and how once
you've gotten to first base, there is still a stretch to home.

[Jerry Bodine]

No argument there, Drew. Really just pointing out AA's recommendation in The Negative that Zn I net density is .10 above fb+f. In Way Beyond Monochrome, p.213, the recommendation is to set the speed point at net density 0.17 and refers to that as Zn I.5 and provides the reasoning for this.