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As far as I know, the change of the exposure moves the negative' density curve left or right only (moves the objects to the different zones), and to shrink or enlarge overall contrast, one has to apply different developments to the film.

Is there other way to affect the contrast range (for instance if you use roll film and cannot apply different developments to different exposures) than by the development, especially, by the use of filters? Are there some nonlinear filters that reduces light not by wavelength but by the intensity?

  • To be pedantic, only color filters reduce wavelengths - ND-filters, for example, reduce the intensity, just as polarizers do (but with different technology behind it, of course). – flolilo Apr 9 '18 at 11:33
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    To be really pedantic, color filters reduce intensity as a function of wavelength, they don't change the wavelengths :P – remco Apr 9 '18 at 11:36
  • @remco well...yes. :-D – flolilo Apr 9 '18 at 12:03
  • Technique sometimes can be as effective as equipment used. – Stan Apr 9 '18 at 19:30
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When shooting color film there is not; what you see is what you get.

When shooting B&W film you have a number of options:

  • the high pass filters in classical yellow / orange / red / infrared sequence serve to increase contrast; these are widely available
  • the considerably rarer low pass blue (or rather cyan) filter has the effect of decreasing contrast

The best online source I know to discuss this in lenght is the B+W handbook - black & white filters are from page 30 on.

The reason why this works is diffraction: blue (and UV) light bends more than red (and IR). So there is more blue in shadows, and less red. Cutting blue off increases contrast, and vice versa.

Red (and infrared) filters clear up some haze and sink shadows; blue (and UV pass) filters add to atmospheric haze and lighten up shadows.

Note that ortho (red insensitive) film has in effect the blue filter built in; there were landscape photographers who were said to prefer it for the way it decreased contrast in shadow areas.

  • “The reason why this works is diffraction: blue (and UV) light bends more than red (and IR)” – this is wrong, diffraction affects long wavelengths more than short ones. However, im most situations, diffraction is pretty much neglectable for all optical frequencies as well as near IR and UV. You may actually be referring to Rayleigh scattering here, which does have the effect that, at least in outside shots, shadows are more blueish than highlights (simply speaking, because they're illuminated by the blue sky, not the yellow sun). – leftaroundabout Apr 9 '18 at 16:20
  • @leftaroundabout thanks, I will study up on the scattering. I am familiar with the effect, as I enjoy shooting landscape in heavily filtered B&W film, but not so much about the cause. – Jindra Lacko Apr 9 '18 at 17:01
  • I'm not convinced that the answer is as cut-and-dried as implied by this answer. There are more than a few ways to accomplish most things. I will present a way that works with either color or monochrome. – Stan Apr 9 '18 at 19:33
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No, not if you mean in the sense that the filter changes transmission as a function of incident intensity. Such a filter wouldn't be useful, as the light that hits the filter is not focused into an image.

What does exist are graduated neutral-density filters (GND filters). These are used e.g. to darken the sky. And that reduces the overall range of intensity values in the image.

The square version is usually preferred, as they can be rotated and shifted up and down to place the edge of the gradient where you want it. Circular GND have the edge of the gradient at a fixed position (usually in the middle).

(note that this is not in contradiction with a non-linear filter being useless: with the GND filter, you look through a passive filter, and the angle of view is important; with a filter that reacts to the incoming light, the angle of view does not play a role, only the intensity)

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Haze or flare will reduce the contrast of a scene. That's why lens designers work to minimize it.

Introducing it in a controlled way will accomplish what you wish.

You can use an air-space between two plano thin lenses and place that into the light path of your system where a normal optical filter is placed.

It would introduce flare to reduce the contrast of the scene without affecting the wavelengths of the scene.

Alternately, you could use a beam splitter or a prism to accomplish the same thing - again, placed where you would normally place a simple "filter."

It's worthwhile to note that flare/haze is non-linear. It affects the shadow areas disproportionately more that the highlights.

  • another example of the controllable haze: a piece of glass covered by dust placed just before the lens. the effect can be further adjusted by changing the dust illumination. – szulat Apr 9 '18 at 19:56
  • @szulat Yes, but that would trash the focus due to dispersion by the dust particles. – Stan Apr 9 '18 at 20:02
  • no, this would happen with e.g. ground glass, but things like dust only add defocused ambient light without affecting the main subject focus – szulat Apr 9 '18 at 20:32
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In black-and-white film, processing is the normal way to attain this. There is no real way to do it with filtration - some filters might cut down contrast incidentally, but will have other effects.

You can do zone-system-type processing effects on rollfilm. The easiest way is to do it on a 120 camera with interchangeable backs. Dedicate a back to a specific type of exposure, and change the back if you want to compress or expand contrast. Another option with 35mm film is to use multiple bodies - which in this day and age is easier than it was in the heyday of film. At the time of writing, you can get some reasonable low-end film SLR cameras for under $20 US. (For some types of photography, like landscape photography, the features of the camera are going to be very secondary to the lens choice.)

You can adjust shadow contrast through flare effects, though. For example, using an uncoated or single-coated lens instead of a multi-coated one will result in more detail in the shadows and less contrast. The degree of this will depend on the amount of light that is being reflected off the elements, so strong side light or back light may be necessary to make a strong effect. You can probably simulate this effect through the use of a filter (perhaps a very dusty one, or some uncoated filters stacked in front of the lens) but you will probably lose some resolution in the bargain.

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