Overuse of the word 'Contrast'.

[Darin Cozine]

One thing that confused me when learning photography is the use of the word 'Contrast' It seems to be used for everything... scenes, lenses, film, developers, paper.

It really confused me in the context of film. Slide film was described as being high contrast compared to negative film. So I would think that it would be good for photographing a high-contrast scene. But in fact slide film can only capture a narrow band of contrast compared to negative film. So the end result looks more contrasty (damn I used that word again).

Wouldnt it be easier if we could use different vocabulary for each context??

[Thilo Schmid]

Darin, no, I don't think so, because the term actually applies to all these things somehow. "Contrast" is the difference between the darkest and the brightest parts of a picture, scene, lens-output, film-density, etc. Slide-film has got a high contrast, because the difference between the film base and Dmax can be as high as 4.0 logD (which is ~1000x "more" black than a print can be) and this has "nothing" to do with the scene contrast it is able to capture. So if the term applies to more than one aspect, there might be a confusion with the reference, but not with the meaning of the word.

[Frank Petronio]

"Contrast" used in commercial printing has a totally different meaning than photographer's "contrast", much to their dismay when proofing press sheets!

I agree, it is an overused term.

[John D Gerndt]

I agree with you about the use of the term. The only defense is to get a grip on the slippery slope of the technical facts of the photographic process. I have been working on it for 25 years.

If you can sort your way through the science of densitometry (and can afford the equipment!) you will be fine. If you are poor like me you’ll have to read a lot and sort through all the truths and half-truths to get to what is real and pertinent.

This forum has been a great source for (mostly) good information. Search the files and ask your remaining questions one at a time and I believe you will be quite happy with your results.

[Rob Tucher]

Contrast is a word like "criticism." There's negative criticism and positive, and many other types but people always complain of too much criticism as if it is only negative. I love criticism when it's positive and take negative criticism when I can learn from it. Contrast can be low, high, or anything in between, and what many people get confused by is that contrast defines levels of separation. More separation means lower contrast, more definition of tone. Lower contrast is fewer tones and less separation. And there's a lot in between this.

[Ted Harris]

If you want to learn more than you ever thought you wanted to know about terms such as resolution, constrast, sharpness, accutance, etc. ..... I highly recommend the book "The Critical Image"

[Ralph Barker]

I tend to equate the vocabulary of any industry with the "secret handshake" - you have to decipher what the terms mean within that context in order to be part of the crowd (club). ;-)

Contrast is one of the terms that can also take on slightly different meanings in various specific photographic contexts, as well. While generally referring to the difference in luminosity between bright and dark areas (the brightest and darkest, actually), and whether the graphical plot of that difference is steep (high) or shallow (low), there are subtle variations in usage that are not universally consistent between photographers. That seems particularly true when people speak of contrast with respect to lens performance. Thus, it is sometimes necessary to expand the discussion in order to disambiguate what the person means.

For example, while I think I might agree with Rob's explanation, I'm not completely clear on what he means by "separation", and would want to discuss that aspect further. Does he mean the total separation in luminosity between the brightest and darkest areas? Or, does he mean the ability to visually separate or differentiate between different, intermediate tones within a "continuous tone" image? (The latter, for me, being close to the definition of contrast when used to describe lens performance.)

[Darin Cozine]

Another thing that is hard to get my mind around:

When I print on VC paper and use a high-contrast filter, I get less tonal detail. But then Platinum and Azo printing, which has a higher contrast range, will yield better tonal detail. UG!

[Conrad Hoffman]

Learn what a paper or film curve (H&D curve) tells you about light coming in (log exposure) versus blackness (density). Contrast = Slope. A steep slope is a high contrast material and should be matched with a short tonal range input (also known as low contrast neg or scene). A mild slope = low contrast, and will match a high contrast neg or scene. Remember that both high and low contrast films and papers still go from black to white. Either one can produce a full tonal range if exposed to the correct range of neg or scene. If I say any more, I'll just confuse myself, but be assured that if you grasp what the curves are telling you, understanding contrast in any context will be trivial.

[Cesar Barreto]

Darin,

Sure, there's lot of abuse on this term and sometimes it can be so meaningful as the word "love" on politicians mouth. But it still can be clearly understood and I usually try the following approach on classes, classifying the different contrast meanings: 1- local and overall contrast - applied to subjet luminance, negative or paper densities 2- subject contrast - luminance range of the subject for itself 3- lightning contrast - wich adds to above 4- optical contrast - thought as 100% on ideal lenses and worse for many reasons wich depends on lens design, flare, misuse, etc.- 5- film contrast - depending on physical nature of particular emulsions (negative x positive film, for instance) 6- development contrast - a major issue on B&W 7- paper contrast - better understood as paper gradation.

What makes things a little harder to understand sometimes is the confusion among different beasts, such as exposure range and paper or film contrast. Both, slide films and short gradation papers (like using high VC filters), for instance, will need short exposure range to show it's full range of densities, or as people say, it's full contrast. Platinum paper needs long exponsure range (or contrasty films), like negative films welcome long scaled subjects (or contrasty subjects). Learning and understanding the whole lot of photo theoretical concepts really helps clearing the scene and our talking about it. And increase the contrast (!) of our seeing. Welcome to the jungle.

[Jay DeFehr]

Hi Darin. I understand your frustration and confusion. Contrast is central to photographic imaging, and a clear understanding of the concept is critical. I intend to make a little animation sequence that will illustrate the concept, but haven't gotten around to it yet. Most photographers that I know are very visual people and respond to visual demonstrations, but I think you can follow in your imagination. Imagine a bar divided into three equal sections; pure white on the left, middle gray in the middle and pure black on the right. This is a very high contrast scale. Now imagine that you can tug at each end of this scale and stretch it, but as you do so, new tones averaged between the two adjacent to them appear. The longer you stretch the scale, the smaller the tonal difference from one tone to its adjacent tones, and the more of them. So a long scale has many steps between white and black, while a short scale has few. I hope I haven't added to your confusion.

[Noshir Patel]

Ok, I'm curious.

Give me a definition of contrast that doesn't have to do with the difference between a lighter value and a darker value (with larger differences referred to as higher contrast).

Sure, high contrast film (that is film that renders a medium contrast scene as a high contrast transparency) is bad for a high contrast scene. It makes sense. One magnifies the other producing a very high contrast transparency (where the supposed ideal is a medium contrast transparency).

Even lens contrast makes sense with this definition. A lens with less flare or whatever will produce a more pure (and thus higher contrast) image than one with more flare (I am using the term flare loosely... not sure if it's quite correct usage). The flare adds light to darker areas in the resulting image, thus lowering contrast (I suppose it subtracts a bit of light from the light areas as well).

Guess I don't see the inconsistency (or I've had the good fortune not to come across people who use the term in a very confusing way).

I suppose if someone used the term high contrast to mean high dynamic range, that would be confusing, but in my mind that usage is simply wrong (possibly even backwards).

[Tito Sobrinho.]

Contrast to me means, rich blacks with detail as well as rich whites with detail and a myriad of grays in between.

[Kaatharine Thayer]

>Contrast to me means, rich blacks with detail as well as rich whites with >>detail and a myriad of grays in between.

Given that definition, is there any distinction in your mind between "contrast" and tonal range? What would you call a print that had only black tones against white paper?

[Tito Sobrinho.]

I called a bad print due to bad exposure and or development . Not to be confused with a Low Key picture that has Zones I, II, III and V. My prints have rich blacks with detail as well as rich whites with detail. I called - excellent local contrast. Called it tonal range if you will.

[Rob Tucher]

Ralph, good point. To me, and gotten from George Tice years and years ago in a printing workshop, more separation is rendition of more shades of gray between black and white. So a print with low separation (high contrast) has black, white, and a limited number of gray tones between them, with a more precipitous jump from one gray to the next. A print with a high degree of separation would have a very large number of decipherable gray tone between black and white and this would appear lower in contrast...because you can see multiple grays inside, let's say, an area that might block up as black only if printed at a higher contrast. It at first seemed counter-intuitive to me but now makes complete sense.

[Kaatharine Thayer]

I think this is an important issue, but my concern isn't that the word is used in different contexts; I'm more concerned about the fact that even if we stick to one context, say print contrast, we don't seem to have a universally agreed-upon language, as is evident from the above discussion.

This lack of clarity over "contrast" has got in the way again and again when I've been trying to help novice gum printers trouble-shoot problems they have with their process; the difference between how we use the word often obstructs my ability to "see," without having the print in front of me, what's actually going on.

Two cases in point: one beginning printer kept insisting that a certain condition resulted in a "high contrast" print. This didn't make sense to me, and after a few followup questions it became clear that what she really meant was that the print was all black; there were no other tones-- no midtones, no highlights, no details in the shadows, all black. Within a couple of weeks of that encounter, another inexperienced gum printer said that a different condition caused her to get a "low contrast" print; again her statement didn't jive with my experience, and finally it came out that what she meant by "low contrast" was the same thing the first student meant by "high contrast": a totally overexposed print with no tonal range, just one dark value across the entire print.

I suspect that the first printer defines "contrast" in terms of DMax: how dark is the darkest dark, regardless of whether there are any other tones in the print. And the second person probably defines "contrast" in terms of tonal range in the same way it's been defined by some in this discussion: if contrast means a long tonal range, just one tone must mean low contrast. For myself, I don't think that the word "contrast" one way or the other has any useful application in a situation where all the tones are blocked and the obvious problem is overexposure. But given these and other confusing discussions, I too have been puzzling about the word "contrast" and the various ways it is used and misused.

When I asked my earlier question, I was wondering how Tito would characterize Harry Callahan's photographs of weeds, say, in terms of contrast.

[Noshir Patel]

Katharine,

It seems to me that a "high contrast print" would be one where the difference between a particular light area and a particular dark area is greater than a "normal contrast print" (whatever that is... clearly terms like "high" have to be relative to something).

A totally black print is certainly not a high contrast print. It is an extremely low contrast print. So, I'd say your analysis of the first printer's terminology is probably correct... a complete misuse of the word "contrast". Of course, at this point the error in printing is probably such that the idea of contrast should be left out of the discussion.

As for high contrast as it relates to tonal range...

In general a higher contrast print would have a longer tonal range compared to a lower contrast print (so long as the entire tonal range capability of the paper is not used by both prints). At the extreme (where both prints are using the entire tonal range the paper is capable of) tonal range would be identical, but the higher contrast print would have a greater difference between two given gray points on the print. There would also likely be more pure white, pure black, or both.

[Kaatharine Thayer]

While it's true that an all-black print has no contrast, therefore technically could be called a "low contrast" print, I still say that the word "contrast" has no useful application in that situation and bringing it in just confuses the issue.

I'm on the same wavelength with Jay about contrast, and with the people who defined contrast in terms of slope. My point, which may have been stated so subtly as to be missed entirely, was that people talk about print contrast in ways that contradict each other, rather than there being a universally agreed-upon way to define contrast. This discussion continues to prove my point, and I'll rest my case and move on.

[Dan Fromm]

This discussion makes me feel like I'm back in a junior high school english class. Compare and contrast common language interpretations of, yes, contrast.

Cheers,

Dan