Are slower films more contrasty or less contrasty than faster ASA films ?

[LabRat]

Depends on the film curve of the individual film... For instance, some modern films have a long toe that records lower shadow detail, but places it lower on the scale...

Testing, testing, testing required...

Steve K

[Jim Fitzgerald]

Not even all rubber bands are the same. And if you stretch any of them too far, they'll snap. Some films are capable of very wide ranges of contrast gamma development; many others are not. IT HAS VERY LITTLE TO DO WITH FILM SPEED PER SE. Some slow fine grained films like Pan F have very little contrast malleability, which the recently extinct Efke 25 had miles or it. It depends what any specific film was engineered for to begin with.

The adaptation of extremely fine show films of the technical or microfilm category for pictorial purposes using special low-contrast developers comes with a big penalty in terms of what range of scene tonality those films will accept to begin with; it can be pretty disappointing compared to film engineered for general photographic usage to begin with.

Drew, I agree with you. I still have a diminishing stash of 8x10 Efke-25 and it will build contrast for days. I've made most of my carbon prints in 8x10 using this film. It is a thicker emulsion and it was a sad day when the factory lost their 99 Yr lease.

[Eric Woodbury]

Without all the technical, yes, I can get more contrast from slower films than from TriX or HP5. FP4 gives me up to N+4. Tech Pan is "unlimited contrast", but in that case exposure is so critical as to be a guessing game. Ilford Ortho provides high contrast, both by development and contrast from the spectral sensitivity.

If you are interested in high contrast from FP4, read anything you can find by John Wimberley.

Have fun. -E

[Bruce Watson]

I am trying to understand how film works with light.

It's a really complex system -- it is very unlikely that any posting in a forum like this will advance your understanding much. Just not enough space, or enough time.

Grant Haist wrote a two volume tome called Modern Photographic Processing. It covers just about everything photographic from Haist time at Kodak. It is the definitive resource for photography up until about the mid 1970s maybe. I'm hardly an expert, but I've read a fair amount of this work -- the local university has a set in the stacks that one can just go read. Fascinating stuff. Very complete.

Another source that's almost as exacting is Adam's book The Negative (book 2 of his series).

Between the two of these sources you could extract the equivalent of a Ph.D in photographic film sensitometry.

There are of course many many more sources.

Basically I would think you'd need to understand how an emulsion is built, how a latent image is created, and how it is developed, and how it is fixed. It took me years, and I'm pretty sure what I learned just scratched the surface and at least some of what I'm sure of is just wrong. Education is like that. ;-)

In black and white photography are slower films more contrasty or less contrasty than faster ASA films ?

This to me is a non sequitur. IOW I don't understand what you're asking. If by "contrasty" you are asking about contrast index (CI), I think CI is largely dependent on which developer you use and how you use it. That is, a given film and a given developer can give you a range of CIs depending on how you use them.

That said, I don't find anything inherent in modern B&W films that make me think "contrasty" is connected to "slower" or "faster" films.

Which is better for a contrasty scene and which is better to use on an overcast day that is less contrast?

Ah, Adams' specialty. Ansel Adams and Fred Archer invented the Zone System more or less specifically to answer this question.

That said, I've successfully used TMY2 developed in XTOL on a very wide range of contrast scenes, from a single stop to around 16 stops. Beautiful prints from both. You can make it work, but it's not automatic.

I was once told that a slower film can absorb more contrast but I am not sure what is meant by that.

Another non sequitur. I have no idea what "absorb more contrast" might mean.

I hope I've at least pointed you in some directions that might allow you to find some answers. If not, feel free to ignore me. Most everyone does... ;-)

[Andreas]

Development of course influences the contrast and the grain. But if it did everything, we would be just happy with a single film and a range of developers.
The film emulsion has by itself some defining characteristics. I was taught to see it as a stack of silver salts of different sizes, ready to catch light. The larger ones are more sensitive and will produce larger grain, the smaller ones less sensitive but finer.
Contrast is just the ability of the developed stack of silver to let through from a tiny bit to a whole lot (and everything in-between) of light from your enlarger/scanner light source.
Silver grains packed in a single layer will allow none or all the light through (lith film), silver grains disseminated in the thickness of the emulsion allow for a wide range of densities.
I guess that the introduction of flat crystals (t-max) and dye-producing developers must have changed this somewhat.
Best
Andreas

[Michael R]

Just keep in mind Ron would also always remind us it's all in the emulsion design. A slow film need not be "high contrast". The classic example was Pan-X - ISO 32 but behaved like any medium speed film with respect to curve shape/contrast.

Of course, a slow speed film with a long scale that behaved "normally" (like Pan-X) eventually became an obsolete thing as evolving emulsion technology (including lessons learned from colour film emulsions) led medium speed films to be as sharp and fine grained as the older slow films. So, today, the slow films available do tend to be high contrast, special purpose things. Pan F is an exception (though a moot point since it isn't coated in LF), being a general purpose slow film but still with a somewhat shorter scale/higher contrast than say Delta 100 which is essentially as fine grained and sharp as Pan F.

It's more a matter of what exposure, and the developer you use and how you use it.
for example, good old "tech pan" film could be exposed at iso 200 and developed in print developer to yield sheer black and white negatives (no mid tones) or at something like iso 24 and developed in special developer and yield a "pictorial" (mostly midtowns) negative. That's an extreme example, most films don't have a sliding ISO like that, but still ... depending on how you expose and what developer you use it will usually adjust the contrast range of the film. ISO in the broadest sense is how film companies describe the photo emulsion's sensitivity to light .. they have a specific routine / methodology they use to determine this.
You might google someone named "Ron Mowery" who sometimes used the nickname "photo engineer" on various websites. He was a retired emulsion scientist at Eastman Kodak who explained these sorts of subjects in depth on a variety of websites like photo.net ...

John

[Andy F]

This was really helpful. Confusing at times but helpful. I just want to thank everyone on the thread.
-Andrew

[ic-racer]

I am trying to understand how film works with light.

The more light the film sees, the darker it will be upon development.

In black and white photography are slower films more contrasty or less contrasty than faster ASA films ?

Films are processed to a specific contrast to match ones enlarger or contact printing setup.

Which is better for a contrasty scene and which is better to use on an overcast day that is less contrast?

Both will work.

I was once told that a slower film can absorb more contrast but I am not sure what is meant by that.

I don't know either.