I'm too late, since Ralph already gave you the answer.
So perhaps a question in return: why do you assume straight curves of infinitessimal length?
Compressing highlights or shadows using exposure is as old as photography is. Have we already forgotten? Wow!
straight curves of infinitessimal length?
Well, yes and no, Mark.
The decision to increase contrast is a decision to lose detail somewhere. If it were problematic, we wouldn't decide we want to increase contrast to begin with.
What and where we drop can be controlled shifting the scene up on the shoulder (if there is one) or down the toe. That last bit is what underexposing does.
By developing longer, the bits that are still recorded are shifted further up the scale again, stretching the range.
Isn't that a contradiction? Something that is infinitesimal probably cannot be seen.
Perhaps you meant, "infinite"?
:confused:
[...]
I don't think underexposure is a good term here.
If we start with a EI 400 film (if developed normally) and change the process to say +2 development, EI 640 becomes a really good estimation of the "proper" exposure based on speed point.
So once we decide that the important bits of our scene will fit nicely on the curve of a +2 negative then our job at the camera is simply placement (and of course composition). i.e. getting the important bits placed on the curve.
To underexpose, IMO, you would need to shoot that EI640 speed point combo at say 800 or 1600 or 3200.
Underexposure, shooting past the tested speed point, would reduce the density of the negative and less density means...? :confused:
I think we're now only discussing semantics.
I say "underexpose", you say "shooting past the tested speed point" or talk about a different "IE".
Underexposure would indeed lead to less density.
Less density means we can still print most of the scene, except the part of the scene for which less density equals no density.
It will also lead to a compression of tones in that part of the scene shifted off the straight part.
If we combine that underexposure (something that already changed contrast) with prolonged development, densities are restored, but the effect of underexposure on what parts of the scene are captured, and how, is not.
Sure, but it's not necessarily making our lives easier.
And sure you should get stronger/more blacks in the print, but the compression of tones, as the curve flattens on toe or shoulder, resulting in a reduction in the separation/contrast.
Still and yet that choice to underexpose is just a placement choice.
From "box speed" this statement makes sense. This is the standard logic for the push/pull world, it's anathema for the expansion/contraction world.
The difference is in the general practical use.
Pushing/Pulling is for getting something usable from something truly under/over exposed, it's normally driven by needing faster or slower shutter speeds than the film in our pocket would normally give us. Ease of printing is a secondary consideration.
Expansion & contraction are for matching SBR to a planned film density range and in turn to a planned paper density range. They make a specific printing result easier.
The difference in use is much more than semantics.
When we print, and we use too "hard" a contrast the print looks ugly, we get a different kind of ugly when we print to "soft".
It's the steepness of the curve that matters here, the rate of change from one tone to the next, not how many tones there are on the negative.
Exposure doesn't change the contrast rate/curve steepness.
Exposure determines placement, which part of the curve we use.
If we plan on a +2 process and shoot the same scene, in the same light, using a 400EI film at ~640 we'll probably get a full curve on the neg, if we shoot the same film at 1600 we are just moving our exposure down the curve some and our exposure may not get up to the shoulder.
The print from the neg shot at 1600 will look darker than the one shot at 640, not more contrasty.
Please, don't use the term "we" as I for one find your reasoning unusual if not confusing.
A film's response to a given amount of light doesn't change unless the development process changes, does it?
Yes it does, predicated on where the tonalities fall on the curve, if tonalities were to fall entirely on the straight line, then the answer would be no. In my opinion that would be a very rare set of circumstances.
Choosing a film curve and exposure carefully to match the SBR we want, should provide the best separation of tones (contrast) possible on the film, correct?
Agreed, however, my interpretation of a scene (SBR) would be markedly different than Brett Westons, I'd like to think it would come down to personal vision /style, neither of us being right or wrong, just different.
Underexposure, without any other change, reduces total density/overall negative contrast, right?
On the face this statement is true, however, most everyone here has correctly coupled less exposure and more development as a means to effect higher contrast. Personally, I do not use the terms "under or overexposure" as I believe those make reference to a constant and in this context the constant is dictated by one's desired look, rather I use the terms "less or more" pertaining to exposure and development.
Sure, a change in the print exposure or print contrast grade is always an option, but underexposure of the film doesn't increase the contrast of the result, we have to make that choice during printing, right?
Negative exposure / development and paper contrast / processing is a multi faceted relationship that can be significantly shaped to one's personal likes and style, it seems to me that so many posters here site "one line bullets" striving to make their point if not pound their chest a bit. That said, at the core of their statements many are correct, however, in practical application there are so many other variables which impact the OP question of "methods to effect more contrast"
In photography many common tasks get packaged together. Pushing and pulling, and underexpose and overdevelop are great examples.
These concepts get packaged so tight that their process becomes dogma, many people think they have to be used together.
Dogma is easy, but it's not always right.
We can simply use a +1 process with normal exposure settings.
Once you have run out of the limited margin you have doing that without adjusting exposure, you too will have to do that "dogma" thing.
Development changes; -1, +1, etcetera... are used adjust the length/height of the curve, the contrast.
Steve this is a good answer for "ME". When I originally asked the question, I had no idea that it would get such a big and complicated response. The thread has taken on a life of it's own and that is not bad but much of the information is too much for me personally. Steve's response in #88 has information that makes sense to me.
Steve if I understand your response, at a given exposure, the light can have more or less contrast depending on the scene...correct? So a given light value will fall at a different point on the curve based on the contrast of the scene??? Correct?
I have been reading Ralph Gibson and he over exposes and over develops to achieve his interpretation of a high contrast scene. Iknow that many of you that are participateing in this discussion know what you are talking about because I can look at your gallery and see what you produce. I may not really understand your answers because it is beyond my level at this point but it makes me think. Steve's response resonates at this point in my journey.
My most recent book "Darkroom" has many different "Greats", including Gibson. Their individual approach shows that many of them don't seem interested in the "nuts and bolts" only in how to get the results that they see in their eye.
If all I want is a little more contrast on film, all I need is a little extra time in the developer.
If the only downside is that I end up 1/3 of a stop overexposed I'm going to be pretty happy and I'll figure out the exposure I like in a roll or two.
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