What is "microcontrast"?

[Kevin Crisp]

Yes, I can use Google. No, I still don't know what exactly it is. Gets thrown around here often, it's sort of the new "bokeh" in terms of fashion. I know the difference between sharp and not sharp, and contrasty and not, but what is "microcontrast" that is any different from those two? Reading posts where people use the phrase (such as "my general impression is that the Japanese lenses have more overall contrast but the German lenses have more microcontrast and may in some cases be sharper...") has not helped.

Thanks.

[N Dhananjay]

Terminology is often used loosely. Contrast is often used to indicate overall luminance range - the ' 7 zone spread', 'high contrast range' etc language. It is also used to indicate the quality of light - flat vs. strong sidelight etc. Micro-contrast is basically contrast in small areas. Do not confuse this with sharpness in small areas. Sharpness is a psychological sensation that concatenates resolution (lppm) and contrast (to what extent the small areas of black and white reproduce as black and white without merging into shades of grey at the borders).

This is what gives you texture - the feel of snow and sand, the smoothness, roughness - basically surface textural information. It is also easiest to lose - if your focus is off, the little dots of black and white merge into grey. If you enlarge too much, you lose this quality. In fact, I think this is the actual appeal of contact prints, especially with development procedures that emphasize adjacency effects which accentuate micro contrast. The older lenses often used in larger formats are not as sharp as modern lenses but contact printed, they produce wonderful micro contrast, sometimes referred to as tonality. Think of it this way - the 4X surface area of 8x10 compared to 4x5 means you use 4X times sliver halides to capture the same information. In the small areas, you have more information on the negative, which trumps the lower resolution.

Hope this helps. Cheers, DJ

[MAubrey]

Zeiss has two pdf's by H. H. Nasse that talk about micro contrast in relationship to other issues surrounding resolution, sharpness, and modulation transfer functions that are worth reading. They should help you.

http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln30_en_web_special_mtf_01.pdf
http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln31_en_web_special_mtf_02.pdf

[8x10 user]

Its the contrast in the finer details of the image (like clarity or USM), versus global contrast which is what we normally just call contrast.

[LabRat]

I don't know the exact meaning, but I assume that it describes that B/W "sweet spot" where there is a (seeming) endless gradation range of silvery tones, that are nicely divided by a crisp acutance, that give the image a "bone structure" apparent sharpness, with endless tones swirling, weaving through it... (I think it comes from nailing the process steps and finding the "sweet spot"...)

In the old Leica/Contax "wars" of the 30's, I have heard that Contax (later Canon + others) had balanced the tones of their lenses so that they were more contrasty, so as to produce a greater "apparent" sharpness (but not as microsharp), where Leitz (later Nikon), had balanced the tones to be less contrasty, but with much more microsharpness... (Then the jury waits, as one goes into the darkroom, and produces results that one prefers over the other make...) So it was a look/design compromise thing...

So on the lens front, we often have older, classic lenses with a longer, smoother gradation, but not as brutally sharp (and flatter contrast), or newer lenses that are ultra sharp, but sometimes cold and hard looking, and contrasty sometimes at the expense of gradation... Sometimes there are lens examples that balance both of these well!!! So what type works with a individual photographer's working style/process??? (And what is preferred???)

One of the famous LF makers had produced a line of lenses for a long time (I think) that were for mainly shooting products in the studio, that had a cold, hard, contrasty, clinical look that helped items always look VERY sharp (Like trying to photograph a ceramic figure on a white background, where the figure often will look soft no matter how well focused!!!) But might look cold/hard doing a landscape (and printing it on a very cold/hard paper???)

Let me get out of here before I set-off an atomic bomb...

Happy Holidays, Everyone!!!

Peace on Earth!!!

Steve K

[Old-N-Feeble]

Lenses, type of film, type of developer, how film is developed and many other factors all play a part but, IMO, the biggest players are subject and lighting. Some will say this is a completely different subject but I consider them linked.

143852 143853

[Paul Metcalf]

Hey Kevin - I think your last name is a great layman's term for micro-contrast.

[bob carnie]

Hi Kevin

From a print perspective I will give you an example that I think applies.

When split printing a long range negative , some workers will flash or even burn with 00 to bring in highlight detail.
Usually this will work and you move on.
What I like to do in this area is to give another burn , but use the 5 filter... This will not affect any of the whites but any region that shows density will darken, thus giving more apparent detail
and basically contrast.

So in a small area we are increasing contrast deliberately .

In PS the soft light tool will give a somewhat same result. different but more effective in the mid tones.

Bob

[Jac@stafford.net]

Some subjects are more susceptible to greater acutance (apparent sharpness). For example photos of long grass, or reeds, and hair can look sharper because of the way the brain/eye works. We can see a single hair in a photo (or spider web on a wall) but not a dot or a contiguous series of dots of the same width as the hair. And as Old-N-Feeble points out, contrasty lighting helps as we have seen with a strongly sidelit white chicken's egg.

[IanG]

Both Leitz and Zeiss went for similar optical characteristics with regard to micro contrast, the difference was between the German approach and the Japanese which became apparent after WWII when war correspondents began using Nikon and Canon lenses on their Contax or Leica cameras.

Steve K, before WWII the older thick film emulsions didn't have the resolving power and along with un-coated lenses meant micro-contrast differences between Leitz and CZJ lenses weren't noticeable, differences in lens sharpness as designs improved and newer lenses were introduced were more important.

It shouldn't be forgotten that choice of developer can also increase or decrease the micro contrast. D76/ID-11 at FS will decrease micro contrast while staining developers like Pyrocat HD & PMK etc will increase it.

Ian

[Bill Burk]

The threads where I have seen Microcontrast discussed... Seems to me the discussion is in relation to film characteristic curves, or maybe better... tone reproduction diagrams, talking about the slope of the curve in a small region being considered.

So with film of a long toe, printed on paper with a toe and shoulder you arrive at an s-curve where there is little "micro contrast" in the shadows, little "micro contrast" in the highlights... but more or less "micro contrast" in the medium grays... And the discussions about what is "good" or "bad" relates to how well the film and paper can hold details in the hard to hold shadows and highlights.

[Kevin Crisp]

It seems to mean many things to many people. But thanks for your comments. If you google the phrase most of the discussion centers on pixels and sensor sizes.

And when I was the high school paper photographer, my mother gave me a rubber stamp for photo credit that said "A Crisp Print."

[Oren Grad]

One can give it a precise definition in terms of MTF: modulation at low spatial frequencies vs high spatial frequencies.

[Taija71A]

What is Microcontrast? "I know it when I see it!" :)

All joking aside... Hopefully, the images from the following Articles will be of some assistance to you!


http://theonlinephotographer.typepad.com/the_online_photographer/2012/08/titletk.html
http://software.canon-europe.com/files/documents/EF_Lens_Work_Book_10_EN.pdf (p. 209).

--
These images will 'Key' your eye in to what is meant by 'Microcontrast'...
Better than any verbal description can.

As you can see from these simple illustrations... Microcontrast has nothing to do with Overall Contrast
(*Of the sort we mean... When we talk about 'say' Paper Grades).

Best regards, -Tim.

[Dan Fromm]

Um, Tim, y'r links shed no light on the subject. IMO the first one sheds dark. In short, I still don't get it.

I think an explanation of how to measure microcontrast, whatever it is, would help me understand what it is.

Oren, y'r explanation is nearly what I need, I think, but I'm not sure its consistent with many of the descriptions that preceded it.

[Taija71A]

As quoted 'in part' from the following Luminous Landscape article by Mike Johnston:

https://luminous-landscape.com/understanding-lens-contrast/

"Many photographers and even some experienced and knowledgeable ones, seem permanently confused about contrast, especially when the word is used to describe lenses. In photography, like the word “speed” (which can refer to the maximum aperture of a lens, the size of the gap in a constant-rate shutter, or the sensitivity of an emulsion), the word “contrast” actually refers to several different things. “Contrast” in photo paper, for instance, or in a finished image, refers to overall (sometimes called “global“) contrast, meaning how the materials distribute tonal gradation from black to white or lightest to darkest.

When we talk about lens contrast, we are not talking about that quality. What we are talking about is the ability of the lens to differentiate between smaller and smaller details of more and more nearly similar tonal value. This is also referred to as “microcontrast.” The better contrast a lens has (and this has nothing to do with the light/dark range or distribution of tones in the final print or slide) means its ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other."

--
For a more detailed 'Technical Explanation' of Microcontrast... Please see pages 16-18 from the following Carl Zeiss Publication:


How to Read MTF Curves by H. H. Nasse.

http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln30_en_web_special_mtf_01.pdf

Thank-you! -Tim.

[johnmsanderson]

amount : 15

radius : 55

threshold : 0

[Jac@stafford.net]

All joking aside... Hopefully, the images from the following Articles will be of some assistance to you!
http://theonlinephotographer.typepad.com/the_online_photographer/2012/08/titletk.html

The posted URL content is a joke because it is a digital manipulation to give simply an impression, and it is entirely wrong, wrong, wrong because it cannot render the original 3D image - among other reasons. The author would do well to pull it.
.

[Taija71A]

The posted URL content is a joke because it is a digital manipulation to give simply an impression, and it is entirely wrong, wrong, wrong because it cannot render the original 3D image - among other reasons. The author would do well to pull it.

As per the TOP Article (http://theonlinephotographer.typepad...8/titletk.html) by Michael C. Johnston...

"These are illustrations only -- Software analogies of what lenses with these properties might give you."
--
Agreed! Yes, illustrations were used in the article... To give an 'Impression' of the real thing.
Individuals of course, are always welcome to contact Mike... With their complaints about his Column:

mcjohnston at mac dot com.

http://theonlinephotographer.typepad.com/the_online_photographer/contact-top.html

Thank-you! -Tim.

“You can please some of the people all of the time, you can please all of the people some of the time, but you can’t please all of the people all of the time.” ~~ John Lydgate. ~~

[Jac@stafford.net]

As per Mike's Article:

"These are illustrations only -- Software analogies of what lenses with these properties might give you."

Enough said...

Emphasis is good. The presentation is a cheap shot fraud, regardless.
.

[Drew Wiley]

I generally use the term in relation to printable negative tonality. It seem that people like to argue how they can make just about any black and white film handle a wide or high range of contrast simply by reducing the development time. True, ala Zone System theory. But then I emphasize why the shape of characteristic curve is also vital, otherwise merely reducing development compresses the "microtonality" of the midtones and highlights in particular. Then, of course, you've go people like Pt/Pd printers who pretty much surf on all that subtle midtone texture. Lenses also come into play. For example, in the darkroom, I can of course vary overall contrast quite easily with modern VC papers, yet certain lenses, namely my various relatively expensive "apo" versions, will allow me to print much more subtle textural detail or "microcontast" than ordinary enlarging lenses. I refer to both cases in terms of tonality, while I prefer to refer to "edge" or Mackie effect more in the context of film resolution. Other folks might use the expression a bit differently.

[Steve Sherman]

Yes, I can use Google. No, I still don't know what exactly it is. Gets thrown around here often, it's sort of the new "bokeh" in terms of fashion. I know the difference between sharp and not sharp, and contrasty and not, but what is "microcontrast" that is any different from those two? Reading posts where people use the phrase (such as "my general impression is that the Japanese lenses have more overall contrast but the German lenses have more microcontrast and may in some cases be sharper...") has not helped.

Thanks.

Everything is subjective, IMHO. The Philadelphia Prison is high in Global Contrast with moderate Micro Contrast while the Penile Colony is Low in Global Contrast and high in Micro Contrast

[Old-N-Feeble]

^^^ But don't those illustrate differences in subject matter and lighting more so than other more technical factors?

[Dan Fromm]

Hmm. Is microcontrast a property of lenses or of film, processing, paper and printing?

[RSalles]

Dan, lenses. The resolution of film, given development, enlargement, could revel/enhance what is given by the lens first. Impossible to create data where it wasn't - except by cheating or manipulation but this doesn't refer to the capture itself as it's post-capture. Zeiss has a lot of documentation about these lens properties but I'm feeling lazy now to search for,

Cheers,

Renato

[Michael R]

Hmm. Is microcontrast a property of lenses or of film, processing, paper and printing?

Lens, film, film processing, printing.

In the context of the negative (for example) it can be helpful to begin with the characteristic curve and proceed to smaller scales, where more variables come into play. But to make a long story short, "micro-contrast" as the term is typically used in non-digital image structure parlance, has to do with the overall subjective impression of edge sharpness. Without getting into MTF, unless resolution is low, it has primarily to do with traditional acutance combined with edge effects.

Something tells me you already know this...

[Dan Fromm]

The disagreement between posts #25 and #26 and the reference to Zeiss in #25 got me to look at the Zeiss link posted in #16. As I understand it, microcontrast is a property of a lens, viz., high contrast at high spatial frequencies. This is inconsistent with my understanding of the relationship between contrast and spatial frequency, viz., that contrast (MTF value) falls with increasing spatial frequency. Back into the rabbit hole ...

[Steve Sherman]

^^^ But don't those illustrate differences in subject matter and lighting more so than other more technical factors?

What Michael R said...see above visual comparisons in lieu of technical jargon absent of visual reference

[N Dhananjay]

It's a property of the system, including lighting. It can be measured - Richard Henry's "Controls in B&W photography" shows some data from microdensitometer readings. But given most of us do not have access to microdensitometers, you need to get a sense of it in other ways. With lenses, MTF curves are one way to get a sense of the microcontrast rendition of lenses. With film-developer combinations, the shape of the characteristic curve can give you some sense of this. Choice of camera position, lighting, filters etc can be used to emphasize or de-emphasize microcontrast.

The way I think of this is that the trade-off between overall luminance range and micro-contrast is the "Robbing Peter to pay Paul" game that we play. Paper base white and max black define the scale ends of our material. You can try to accommodate a very long luminance range (white sun in the sky to black cat in the shadows, all in the same picture), but the only way to do it is to rob all the intermediate areas of micro-contrast. Think of the typical N- processing done for this purpose. What we are doing is reducing microcontrast everywhere to accommodate the longer luminance range - for e.g., let's say there was a concrete floor in shadow the cat was standing on. You could get some texture in the floor, but engage in N- processing and the floor will merge into a dark grey or black. The same thing will happen across the scale - the wall that was sparkling with texture without the need to include the over bright sky in the picture will, with N- processing required by including the bright sky in the picture, drop into a more or less uniform grey tone - how much it goes towards uniform grey depends upon how much micro contrast there was to begin with and how much the processing is pulled. Basically, little areas that had variation in densities will now merge into a sort of average. But because you do this, you are effectively stealing little bits across the scale. In other words, you have some extra bits of the scale to play with - you can print to drop the floor to black but now you have some room at the upper end to get the sky to print with some tone to it.

All forms of art have these problems. Painters have it worse in some ways, better in others. Their materials have a smaller range. Typical B&W papers will have a paper base white to max black range of about log density 2 - about 7 stops (or doublings of luminance), some papers are even better. Typical paints have much less - along the lines of 5 stops or so. So, their material fundamentally have less range. But they have evolved a number of very interesting ways to deal with this - involving interesting games with implied local contrast using value, color etc. Picasso once said, "Some painters paint the sun as a yellow blob, others find a way to make a yellow blob of paint into the sun" (not an exact quote). If you look at impressionist paintings - an example would be Monet's "Waterloo bridge, sunlight effect" - it is certainly not 'real' - but the use of complementary colors of nearly the same hue creates a shimmering sense of contrast because of the way the eye-brain handles this kind of contrast. All painters learn early the trouble with trying to paint the sun with the highest value paint (i.e., white) - it never works. You have to find other clever ways to imply the seemingly bigger luminance raneg with the limited materials you have. Chiarascuro painting will often reduce contrast dramatically in the shadows so that there is more contrast to play with in the brightly lit areas. Most painters learn a trick early - they will paint something like an adjacency effect to increase local contrast a bit - at the border where a darker and lighter shade meet, they will make the dark a little darker and the light a little lighter - another manipulation of local contrast to keep some room in the overall contrast or luminance range, which is required for other parts of the image. And so on.... It is all illusion. In photography, we have a material that has a longer range but less room for deviations from what is 'real and out there'. We have some controls - filters, dodging and burning etc. But we cannot manipulate local contrast quite as deftly as painters can.

But in some sense, I think that is what makes these mediums so interesting. The illusions they create tell us something about ourselves. And that is probably the most interesting thing about art.

Cheers, DJ

[Michael R]

Nice to see a mention of Henry :).

I largely agree regarding robbing Peter to pay Paul. Said another way, "no free lunch". However there are some ways around this when it comes to reducing total contrast while maintaining and/or increasing "micro contrast". There are a few developers that will tend to exaggerate edge effects even as they reduce total contrast. Of course, the emulsion is critical variable in that particular equation. A second trick is the use of unsharp masking in printing, which can exaggerate "micro-contrast".

[Drew Wiley]

I sure as hell wouldn't call something that can be visibly identified with your eyes and deliberately altered by known technique merely subjective. For example, I
came up with a very nice set of prints last week of a particular neg, having excellent tonal detail all the way from the highlights into the shadows, and still with
bold overall contrast; yet I still intend to reprint it using a subtle unsharp mask to tweak microcontrast ever so slightly. It's such a subtle change that a casual viewer might not even notice it under glass. But I can tell the difference. I want what I want. And no, using this methodology, I am NOT robbing Peter to pay Paul. I'm having my cake and eating it too. However, I have seen cases of just too heavy a hand using masking which became conspicuous and counterproductive. Edge effect can also be distinctly enhanced this way, but overdone, it will resemble that heavy-handed digital equivalent we see all too often.

[Michael R]

Drew, the point is that concerning negative development, total contrast, local contrast and micro contrast all move in the same direction. Thereafter (in printing) there are things we can do. Local exposure adjustments (burn/dodge) at mixed contrasts can change local contrast in relation to total contrast, and unsharp masks can alter micro contrast in relation to total contrast.

[IanG]

Drew, the point is that concerning negative development, total contrast, local contrast and micro contrast all move in the same direction. Thereafter (in printing) there are things we can do. Local exposure adjustments (burn/dodge) at mixed contrasts can change local contrast in relation to total contrast, and unsharp masks can alter micro contrast in relation to total contrast.

Not with all developers, over development (and over exposure) can kill micro contrast and of course the choice of developer is critical as is agitation and dilution to get the best micro-contrast.

Ian

[Luis-F-S]

Something that people who worry more about writing about pictures than actually making pictures worry about. L

[Old-N-Feeble]

Something that people who worry more about writing about pictures than actually making pictures worry about. L

Stone??

[Drew Wiley]

Michael, masking can do all kinds of things. You can target just part of the overall contrast range if you wish. I don't view it as a silver bullet, but as a very valuable tool set when needed. For example, I once routinely overdeveloped 8x10 HP5 negs "thick negative" style, in order to accentuate edge effect and expand midtone contrast. But even with the best VC papers, I was masking dependent to rein in everything. But the net result was often worth it. Yet generally, it's simpler
for me just to use a film with a straighter line like TMY or formerly, Bergger 200. I often never know until I print something, look at it a week or so, and decide
whether yet another tweak would benefit or not. Like many other people, I like to print certain negs several different ways, and might like all of them, yet for different reasons. I seldom make two prints exactly the same.

[Steve Sherman]

I sure as hell wouldn't call something that can be visibly identified with your eyes and deliberately altered by known technique merely subjective.

Drew, the two posted images are "subjective" when compared with one another. The fact that no one has mentioned a Reduced Agitation technique in concert with a Pyro based developer really limits the discussion. There are so few who really give the technique any credence when in reality in the hands of a negative maker who understands the power of Reduced Agitation techniques can match most any negative masking technique while preserving the subtlety of organic transition of tone. The actual characteristic curve of the film is changed organically rather than artificially via secondary masking. Without question this subtlety transitions to the print yet still leaves all Split Contrast printing techniques at the disposal of the maker.

[Michael R]

You have to start with some parameters held constant. All other things being equal (film size, exposure, emulsion, developer, agitation frequency, magnification), as total contrast is increased/decreased, local and micro contrast will follow. However changing those variables can have effects on the relationship between large-scale and "micro" contrast. A hypothetical example for a given film (without getting into specific developer details):

Starting point: Development to normal contrast index in a general purpose solvent developer, with normal agitation

Scenarios for lower target contrast index relative to starting scenario:

1) Same as above, with shortened development time: In comparison to the starting point scenario, total contrast, local contrast and micro contrast will all be lower

2) Change to low-sulfite/dilute developer with minimal agitation: In comparison to the starting point scenario total and local contrast will be lower, but micro contrast might be maintained or possibly increased

These are gross generalizations meant as an illustrative example. Also note the discussion has been limited to contrast effects.

@Drew: There are many different types of masks as you know. I'm referring here only to "classic" unsharp masks, which are normally designed to reduce contrast at all scales higher than "micro", allowing the negative to be printed at higher contrast, thus boosting micro/edge contrast relative to total and local contrast. This can enhance the overall subjective sense of crispness and delineation of detail.

[IanG]

Drew, the two posted images are "subjective" when compared with one another. The fact that no one has mentioned a Reduced Agitation technique in concert with a Pyro based developer really limits the discussion. There are so few who really give the technique any credence when in reality in the hands of a negative maker who understands the power of Reduced Agitation techniques can match most any negative masking technique while preserving the subtlety of organic transition of tone. The actual characteristic curve of the film is changed organically rather than artificially via secondary masking. Without question this subtlety transitions to the print yet still leaves all Split Contrast printing techniques at the disposal of the maker.


Something that people who worry more about writing about pictures than actually making pictures worry about. L

Some of us put this into practice making pictures, I don't take it as far as Steve Sherman but I respect his techniques. So writing in our cases comes from experience not theory.

Ian

[IanG]

You have to start with some parameters held constant. All other things being equal (film size, exposure, emulsion, developer, agitation frequency, magnification), as total contrast is increased/decreased, local and micro contrast will follow. However changing those variables can have effects on the relationship between large-scale and "micro" contrast. A hypothetical example for a given film (without getting into specific developer details):

Starting point: Development to normal contrast index in a general purpose solvent developer, with normal agitation

Scenarios for lower target contrast index relative to starting scenario:

1) Same as above, with shortened development time: In comparison to the starting point scenario, total contrast, local contrast and micro contrast will all be lower

2) Change to low-sulfite/dilute developer with minimal agitation: In comparison to the starting point scenario total and local contrast will be lower, but micro contrast might be maintained or possibly increased

These are gross generalizations meant as an illustrative example. Also note the discussion has been limited to contrast effects.

@Drew: There are many different types of masks as you know. I'm referring here only to "classic" unsharp masks, which are normally designed to reduce contrast at all scales higher than "micro", allowing the negative to be printed at higher contrast, thus boosting micro/edge contrast relative to total and local contrast. This can enhance the overall subjective sense of crispness and delineation of detail.

Missing from your list is the tanning effects of some developing agents which can increase the micro contrast in areas of very fine detail,

There's also the effects of Iodide in the film or formerly in some high acutance developers, This may explain why Rodinal in particular gives very good micro-contrast with T0grain and similar films. It falls into your low sulphite, dilute category.

Ian

[N Dhananjay]

I'm sorry to disagree but you are not having your cake and eating it too. You are still robbing Peter to pay Paul - Peter just doesn't realize it, for one reason or another....

I did not mean to suggest that you cannot make choices that let you get both overall luminance range without sacrificing micro contrast but these are small effects and usually involve a compromise elsewhere in the system. Tanning developers like pyro give you enahnced micro contrast due to adjacency effects and that is part of their appeal, although you give up other things there (speed, grain etc.). Masking can help, for sure - assuming you have some micro contrast to begin with on the negative - no masking technique is going to give you texture on a smooth surface (barring process artifacts). And to keep some semblance of visual logic within the picture plane, you cannot be heavy handed with it. In other words, it helps make those small adjustments that make such a large difference to an aesthetic response, but it does not change the logic of the system.

Within any given system you have adopted, there is always a ceiling your head will butt up against. Just for purpose of illustration, assume you have two large tonal areas - say Zone III and Zone IX, next to each other. You want these two areas to show up as zones III and VII. Each of these areas, obviously, also has texture, or micro contrast and getting that to look 'right' is important. So let us say the Zone III area has smaller regions of tone varying from Zone II to Zone IV. It really does not matter how you approach this - you can pull develop, you can process normally and dodge and burn, use masks etc. But there is simply no getting away from the fact that you have only a scale of paper base white to max black. If you do an N-- film development, we know you will compress the scene such that the zone IX area will appear as zone VII but micro contrast across the whole picture plane will be lowered. So, if you print this negative to get those areas at zone III and Zone VIII, local contrast or micro contrast across the whole scene will now be lower. So you could move to a higher grade paper and do some dodging and burning, or use masking techniques etc. But what is still going on here? Remember you have to get those areas to have an overall look of Zone III and Zone VIII (and all the other zones looking right) but with the appropriate local contrast. Take the Zone III area - you want this to have a micro-variation going from Zone II to Zone IV. Given the N-- processing, this is going to require a higher contrast paper coupled with dodging and burning or a contrast mask or something else. But whatever it is, when you increase the contrast in that region, you are increasing the amount of the scale used to render that region. It has to come from some other part of the scale. If you just bumped up the contrast here without thought for anything else, you get the contrast here looking right i.e., from Zones II - IV. But your original picture may have also had an area of Zone IV (with micro contrast ranging from Zone III-V), which got lowered in the N-- processing. So now you might have the internal visual logic of the picture fracturing because a part of you Zone III area has bits of it which are of higher value than the Zone IV area. If you keep pushing everything up the scale in an effort to keep the internal logic sound, eventually you run out of room at the other end. Your Zone VII area which had an upper micro contrast end of Zone VIII is pushed off the scale into and beyond paper base white.

Now all these techniques work. And that is usually because we have holes in the scale for the picture we are making. If your picture has only Zone III, IV, VI and VII - i.e., no Zone V - then you can steal from this unused region of the scale and use that in the other regions. And sometimes, this kind of stealing does not affect the internal visual logic of the picture. So, some of the light parts in the shadows may indeed look unrealistically brighter than the dark parts in the lights - but these may be separated enough by distance that it does not wreck the illusion.

The point is there are a huge number of interlocks and we make choices and trade offs, hopefully in a reasonably intelligent manner, that gets us what we want while giving up something we don't care about that much. But in order to make these choices intelligently, you need to think of things both at the level of detail and of the system as a whole.

Cheers, DJ

[Michael R]

Missing from your list is the tanning effects of some developing agents which can increase the micro contrast in areas of very fine detail,

There's also the effects of Iodide in the film or formerly in some high acutance developers, This may explain why Rodinal in particular gives very good micro-contrast with T0grain and similar films. It falls into your low sulphite, dilute category.

Ian

I more or less agree. Tanning developers would fall under my "low sulfite" category, but I didn't want go into any detail on the types of developers, developing agents, iodide content etc. I was just trying to give an illustrative example using some broad generalizations.

[LabRat]

I more or less agree. Tanning developers would fall under my "low sulfite" category, but I didn't want go into any detail on the types of developers, developing agents, iodide content etc. I was just trying to give an illustrative example using some broad generalizations.

Yea I agree, and there's different ways to skin a cat...

Seems to me that some one shot/diluted film developers (low sulfite), that go into partial exhaustion, gives me controlled highlights, and edge effects over the scale routinely... Nice grain/nice scale, day or night, easy to print/little dodging/burning without changing the paper grade much at all... And too many tones to start counting!!! And looks natural/organic...

One funny thing I have noticed while louping a neg for printing, is that sometimes there is a plain wall in the subject, that starts to have specks or shading on it... I think something is wrong with the neg, but looking closer, I see that the film/process picked-up microshadings of dirt or texture on the wall surface when using my sharp lenses... I realized that it is something with the high resolution, that I now call "the dirty layer"...

But no more details... The OP was asking "what", not "how"...

Steve K

[Drew Wiley]

All the tricks add up. Tanning developers, more responsive VC papers these days, paper developer tweaks, better enlarging lenses, supplementary masking in certain cases. In other words, microcontrast isn't such an abstract subject if you have means to make it visually obvious in relation to prints before you knew all
those tricks, which was certainly the case with me, though I do sometimes go back to negs from my D76, D23, and Dektol days and significantly improve the prints with at least portions of my newer tool kit, meaning what I switched to decades ago.

[Drew Wiley]

D - The Zone System is simply a shorthand tool for facilitating predictable printing results. It isn't sensitometry per se, but a practical application of it. Same goes
for what I say about having my cake and eating it to. I'm referring to the practical end result. What masking does, if one intelligently applies it, is to selectively
reconfigure the characteristic curve of the film in relation to the specific printing application. So the internal contrast of chosen "Zones" can indeed to expanded,
even when reining in overall contrast if necessary.

[Nodda Duma]

The disagreement between posts #25 and #26 and the reference to Zeiss in #25 got me to look at the Zeiss link posted in #16. As I understand it, microcontrast is a property of a lens, viz., high contrast at high spatial frequencies. This is inconsistent with my understanding of the relationship between contrast and spatial frequency, viz., that contrast (MTF value) falls with increasing spatial frequency. Back into the rabbit hole ...

Hi Dan,

No rabbit hole jumping:

One thing to keep in mind is that optical bandwidth is much greater than the typical sampling frequencies of film.

So really, "high" spatial frequencies for film (or a focal plane array) are moderate as far as the lens is concerned.

So consider this:

When I'm doing a lens design, given enough design variables I can "push up" the MTF at moderate spatial frequencies by trading off performance at higher spatial frequencies. This is all done under the diffraction limit. This type of trade-off will affect micro-contrast. Where and by how much depends on the requirements of the design.

Keep in mind an f/2.5 optic has a polychromatic diffraction limit MTF value of 0.9 or so at 70 lp/mm...up to 0.75 for a production lens after tolerances. That's a lot of design leeway and the high (for film) spatial frequencies won't necessarily be low contrast (i.e. 20% or less).

Many times I won't artificially manipulate the MTF, leaving it a monotonically descending curve since it's a simpler solution, but I have played those games in the past. Doing that currently, in fact, on high resolution imaging lens.


Veiling glare and control of stray light also plays a part.. I tend to reduce veiling glare to maximize contrast in my designs but using it as a design variable (opto-mechanics) can also soften high contrast transitions in an image.