tonal charcter of films

i read many posts, on many boards, about how this film has better tonality than this film etc. But, how can one film have better tones than another if we have certain systems (zone) to choose the tones you want? i know how the zone sytem works, expose for shadows, develop for highlights. so, unless all films of the same type, i.e. panchromatic, are capable of the same tonal reproduction, then such a sytem could not exist.

i start to think that maybe, since you expose for shadows and develop for highlights, that the midtones sort of fall into place, and this would be where certain films differ. if not, then the only area i can see difering is grain, and possibly accutance, but even accutance is effected by tone contrast. so, any clarification would be appreciated.

Different films have different spectral sensitivity. When I switched from APX 100 to Fp-4, I didn't have to use as much filtration for the sky as it is less sensitive in the blue range. Films can have the same tone range, but the colors as represented in tones, can be different in relation to each other.

Different films have different curves. One may have clearly defined shadows and a long shoulder, another the reverse. It is about local gradation.

In addition to the above observation about spectral sensitivity, the Zone system lets you place Zone 1 and Zone 8 density, but the line between them isn't necessarily straight, and the way the high values separate or shoulder above Zone 8 can have a significant effect on the way the final print looks.

LoveMinusZero said:

i read many posts, on many boards, about how this film has better tonality than this film etc. But, how can one film have better tones than another if we have certain systems (zone) to choose the tones you want?

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I've noticed this too and I wonder if many of these opinions are based on minilab results where the photographer has no control over development and printing of the film. When I read things like "this film has weak blacks" or "this film has poor contrast" I wonder whether the photographer is making the exposure and turning the film over to someone else to process and print because with development controls, belive me, there are very few modern films that are limited in their contrast or ability to record a pleasing range of tones.

That said, getting a film/developer/paper match that pleases you is based on several factors:
* Spectral sensitivity of the film (already discussed in this thread)
* Natural density curve of the film
* Film development
* Printing paper curve relationship to film curve

I think the goal is getting adequate local contrast in the important parts of the print, and there are many film/developer/paper combinations that will accomplish this!

--Philip.

felipemorgan said:

I've noticed this too and I wonder if many of these opinions are based on minilab results where the photographer has no control over development and printing of the film. When I read things like "this film has weak blacks" or "this film has poor contrast" I wonder whether the photographer is making the exposure and turning the film over to someone else to process and print because with development controls, belive me, there are very few modern films that are limited in their contrast or ability to record a pleasing range of tones.--Philip.

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There ar films, and then there are films. Beffore I say anything, let me say quickly that it depends tremendously on what kind of print you want to make and how... Darkroom materials can only handle a certain density range in a negative, unlike platinum or scanning and printing via inkjet.

That said, if you look at a TMax 100 negative vs Efke 25, there is a huge difference. The Efke is full of life, midtone separation, where the TMax is flat and dead.

If you print contrasty, it doesn't matter. But if you like those rich midtones, you can't compare film with lots of silver to film made with TGrains.

FWIW, I do process my own film and I am not a beginner.

Depending on the way it is processed, TMAX can give you any look that you want. I don't know the specifics but it can give you huge shoulders. Since I am not big with experimenting with film/developer combinations I just use efke.

lenny said:

That said, if you look at a TMax 100 negative vs Efke 25, there is a huge difference. The Efke is full of life, midtone separation, where the TMax is flat and dead.

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what is the shoulder? also, i said same sensitivity films, panchromatic. i mean, won't the "normal" development place all the tones where they are in realtion to the meter reading of their brightness? i.e. if a scene has meter reading of zone V and VII , and you have figured out the ISO for the developer and film combo, will normal development place both areas of the scene that the meter read zone V and VII, in zone V and VII in the negative?

"Panchromatic" covers a range of possibilities. Some panchromatic films have more red sensitivity, for instance. T-Max films are closer to the spectral sensitivity of B&W video than they are to, say, Tri-X.

The "shoulder" is the portion of the curve where contrast starts to decline in the high values, as density approaches Dmax. The "toe" is the opposite portion of the curve near the threshold of exposure.

what is the curve? my whole confusion is in that the zone sytem allows you to place tones in any zone, so how can one film have better tones than another, if the same tones are possible? also contrast, since it is just differnce in tones.

This about says it all.

The most important of the two for me is the shape of the curve of the film/developer combination, and how that curve interacts with the curve of the printing process.

Some films have very long toes, which result in great latitude in the shadow areas, but poor separation (another way of saying muddy shadows), while others have signficant shouldering, which can lead to compression of highlight detail. In general my own inclination is for films like FP4+ and TMAX-400 that have short toes, relatively long straight line sections, and little shouldering.

Choice of developer can play an important role in determining curve shape. Compensating developers tend to cause shouldering in the highlights, something also seen with some Pyro developers when printing on VC papers. The result is similar but the mechanism is different.

In short, people who understand the relationship between film and paper curves can usually look at the two together and come up with a pretty good idea as to how the tonal values will be conveyed on the print.

Sandy

felipemorgan said:

That said, getting a film/developer/paper match that pleases you is based on several factors:
* Spectral sensitivity of the film (already discussed in this thread)
* Natural density curve of the film
* Film development
* Printing paper curve relationship to film curve

I think the goal is getting adequate local contrast in the important parts of the print, and there are many film/developer/paper combinations that will accomplish this!

--Philip.

Click to expand...

avandesande said:

Depending on the way it is processed, TMAX can give you any look that you want. I don't know the specifics but it can give you huge shoulders. Since I am not big with experimenting with film/developer combinations I just use efke.

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I disagree. I have a particular type of look in mind and I haven't got it yet. I have a few more ideas and it won't get there with any commercially available developer.

LoveMinusZero said:

what is the curve? my whole confusion is in that the zone sytem allows you to place tones in any zone, so how can one film have better tones than another, if the same tones are possible?

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There may be 9-13 zones, or however many you want, depending on the system you use. However, there are many more shades of gray than that. Thousands, perhaps. If you took a 21 step tablet and you eliminated every other shade, you would still have a full range, you just wouldn't have separation in the midtones...

If you develop some Efke 25 in PMK and compare it to a TMax neg, you will see the difference immediately. Midtones are flattened...

I guess each film/dev treats the "zones" in a different manner
Me thinks it all depends on the way the silver crystals are formed in the process of making each emulsion, which determines how the film will react to light getting to it.

The old school films had a wide distribution of silver crystal sizes and give a more organic look
The TMax/Deltas have a narrower distribution of silver crystal size and give a different look.

Then comes the problem of using X Y or Z developers.........

i dont understand what the curve, toe, shoulder etc are?

Have a look at this site. It may clarify some of these terms for you.

www.phototechmag.com/sample-nd04/Bondcurveslow.pdf

Sandy

LoveMinusZero said:

i dont understand what the curve, toe, shoulder etc are?

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LoveMinusZero said:

what is the curve? my whole confusion is in that the zone sytem allows you to place tones in any zone, so how can one film have better tones than another, if the same tones are possible? also contrast, since it is just differnce in tones.

Click to expand...

The objective characteristics of a given film are usually described in a H and D curve. This is a graphic way of expressing density changes relating to defined differences in exposure changes at a given development (time, agitation, and developer choice/dilution)

Most films that you encounter will not be linear in their response to differences in exposure when the development conditions remain constant. In other words (using zone system speak) if you expose a film at zone one it may exhibit a difference in measured density of .04 units above FB+fog. Yet as you give the film a zone two light exposure it may move .07 above FB+fog.

Yet you will find as the exposure increases into Zone III and above the density change between zones may increase as much as .12 between different zones. The area in which the beginning densities change very little is determined as being the toe of the film's characteristic curve.

The area of the curve in which the density increases linearly will be termed the straight line of the characteristic curve.

When you reach the upper densities of the film exposure you will find, in most films that the film density changes once again begin to flatten out. They do not physically decline...the do begin to flatten in their response to changes in exposure. This region will be termed the shoulder of the film characteristic curve.

These measurements in film density are accomplished by using a transmission densitometer.

Just as film is capable of being described graphically in the above manner, so can paper be described by changes in measured reflection density and not transmission density as is the case with film. The papers response and regions termed the shoulder and toe are reversed on paper from those of the film.

Let me add to Donalds post and help out or confuse you even more.

An H&D curve belongs to a family of curves called a cubic spline.

If you multiply the film curve x print paper curve you get a third curve which is the curve of the final print. The slope of the mid scale of the final print can be easily determined by multiplying the slope of the negative (usually about 0.6) times the paper (about 2.5 for grade 2) and then you have the final print slope which is 1.5.

You will see that the toe of the paper and the shoulder of the paper compresses the slope of the film with loss of data. This causes loss of detail in highlights and shadows and is why you want your entire original scene to fall on the straight line portion of the film, and not on the toe or shoulder. This is why the negative is built with low contrast and long latitude, to reinforce these properties. Of course, you will always have toe and shoulder in the print due to the print paper.

Variations in overall length of the straight line portion of the film and paper, and the shape of the toe and shoulder of both contribute to the feel and beauty of the final print. This is a result of selecting the best film, paper and developer for the subject being photographed.

Another comment is important here. The actual amount of silver coated in film or paper has no exact relationship to density. Having a silver rich film or paper is a true myth in photography. In fact, more silver increases turbidity and therefore can reduce sharpness. The best level of silver halide is determined by optimization of speed, grain and sharpness. That may give a low silver film that has better properties than one with high silver or vice versa.

PE

Plotting those curves

Very interesting thread, it's answering some of my concerns in another thread.

By the way, how do you guys measure the curve of a film/dev combo? Is it by making a grey card exposure for Zone I to XI and then taking a densitometer reading of each exposure (given that you've determined your personal film speed)?

LoveMinusZero said:

i dont understand what the curve, toe, shoulder etc are?

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This is less accurate then some of the previous posts, but might be easier to visualize. It also oversimplifies greatly the measurement examples used (they actually need to be plotted logarithmically).

Negative film, once developed, responds to light by turning darker (it becomes more dense). You can track the film's response to light by creating a graph, which reveals the film's "curve".

The graph is created by measuring the light exposure that hits the film, against the density that the film attains. The graphs show the amount of light exposure on one axis (usually the horizontal), and the amount of density attained on the other axis (usually the vertical).

If you could create a film whose graphed response showed no toe, or no shoulder, it would have no density when no light exposure hits it, and a certain amount of maximum density when a certain threshold amount of light exposure hits it, and in between, the graph line would be a simple slanted (and rising) straight line. Three times the exposure, would correspond to three times the density (if measured in the right way).

In the real world, at the beginning of the line (the toe, where light exposure is low) the line starts flat and begins to curve up, until it reaches the straight part. In other words, when the exposure is low, if you triple the exposure, it may result in the density increasing less than three times. Practically speaking, this means that density differences in the shadows (and the details they reveal) are hard to see, and not clearly differentiated (sometimes referred to as muddy shadows).

Also in the real word, at the top of the line (the shoulder, where light exposure is high), the ability of the film to add density with an increase in light exposure begins to come close to the point of maximum, where more light exposure won't make a difference, because the film is as dense as it can get. The shape of the line starts to curve here as well, as it transitions from a slanted (and rising) straight line, to (eventially) a flat horizontal line. In other words, when the exposure is near the maximum, if you triple the exposure, it may result in the density increasing less than three times. Practically speaking, this means that density differences in the highlights (and the details they reveal) are hard to see, and not clearly differentiated (sometimes referred to as blocking up the highlights).

In the straight line portion of the graph, if the rise of the line is shallow, it means that density differences in the midtones (and the details they reveal) are hard to see, and not clearly differentiated (also sometimes referred to as muddy midtones).

The nature of the film itself affects what the shape of the line is, as does the developer chosen, the development technique used, and the sensitometric techniques used when testing.

When you turn to printing the negative, the film's "curve" interacts with the printing technique and the paper's "curve", as influenced by the paper's development.

The resulting response of the film (and developer, and technique, and printing paper, et al) to an image has a particular appearance, which is sometimes referred to as "tonality".

I hope this helps.

To all those here whose training, knowledge and experience are much more extensive then mine, all comments, critiques and corrections are welcome.

Matt

avandesande said:

Depending on the way it is processed, TMAX can give you any look that you want. I don't know the specifics but it can give you huge shoulders. Since I am not big with experimenting with film/developer combinations I just use efke.

Click to expand...

While I think that TMAX is a great film after spending 3 monthes with Efke-25 I don't see going back to TMAX.

so, depending on the film/developer, each stop does not correlate to each zone, and 2 stops change may be only one zone change? also, if some films see colors different shades of gray, if you exposed something at middle gray,Zone V, but the film sees that color as darker than what the brightness level dictates, it would turn out, say, zone III?

LoveMinusZero said:

so, depending on the film/developer, each stop does not correlate to each zone, and 2 stops change may be only one zone change? also, if some films see colors different shades of gray, if you exposed something at middle gray,Zone V, but the film sees that color as darker than what the brightness level dictates, it would turn out, say, zone III?

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Yes, you are correct.

What I am about to say is not to be interperted as Zone System Bashing....

The Zone System does have several distinct failures. You have identified one of them.

It is much more appropriate, in my understanding, my observation, and my education to think in terms of the net density range of the camera negative and to have that correspond to the exposure scale of the material upon which that camera negative is printed.

Again, Donald is correct when he says that the "net density range of the camera negative" must match the "exposure scale of the material."

Perhaps an easier way of saying this is to remember that our eyes can see a large amount of contrast, certainly more than film. Film sees a greater range of values than the paper. The idea is to squeeze the contrast range we can see into the negative in such a way as to be able to print it on the paper of our choice. I like to think of the paper as a constant and the film as the variable. The trick is to take a scene, meter the high and low values, expose for the low value you want to capture and then develop for the highlights you want to place on the paper. When it works, it looks great! tim

mhv said:

Very interesting thread, it's answering some of my concerns in another thread.

By the way, how do you guys measure the curve of a film/dev combo? Is it by making a grey card exposure for Zone I to XI and then taking a densitometer reading of each exposure (given that you've determined your personal film speed)?

Click to expand...

Actually the way that I determine the curve of a film is to expose the film to a calibrated step tablet or wedge. When one does it that way the exposure will enable you to find both the speed point or EI of the film and also then determine the characteristic curve of the film by reading the corresponding negative ransmission densities.

This is at departure from what the Zone System practice indicates but it is far more accurate in my experience. Hope that this answers your question.