What is "microcontrast"?

[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".