Beware of Chromogenic B&W Films

[Steaphany]

The Traditional Photographer's
Most
Un-Wanted

Kodak BW400CN 135-36 Professional Black & White (Chromogenic C-41) Print Film (ISO-400)

Ilford XP-2 Super 135-36 Black & White (Chromogenic C-41) Print Film (ISO-400)

For Crimes and Actions Against Traditional Photography:
For producing negatives that contain No Silver
Must be processed by the C-41 Color Chemistry, Not D-76
For images comprised of Dye Clouds, not Grain
Forcing prints with Color materials and RA-4 Color Chemistry

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How many reading this were already aware that C-41 Color Negative film has spawned off, and gone full circle with, a B&W descendant ?

Motivated by processing lab economics, Chromogenic B&W film is processed by the same chemistry and processing equipment as common C-41 color negative film. This means the lab does not need to maintain a separate B&W process line for the occasional B&W roll that comes through their doors. If you are a traditional photographer or a digital shooter looking to expand into B&W film for a natural and characteristic image grain, you best familiarize yourself with the characteristics of these newer films. First and foremost, just like color C-41 processed negatives, the final image comprises dye clouds centered where each original Silver Halide crystal and the resulting metallic Silver grain was once located, but where color film employs three dyes, Cyan, Magenta, and Yellow, Chromogenic B&W film employs a single dye, Black.

To better understand this, lets look at some images. Here is what the film you load into your camera looks like:

Each granule in this image is an actual Silver Halide crystal waiting for a sufficient number of photons to allow it to produce a grain of metallic Silver when exposed to the developing solution. For the granules which fail to produce a grain, they are subsequently dissolved away by the fixer.

Now, to see the results, the images that follow all had a low enough exposure to permit observation of individual grain particles.

Here is a representation of a processed traditional B&W film, derived from a later image for illustrative purposes:

All the Silver Halide crystals lacking sufficient photon absorption have been dissolved away and what remains here are the metallic Silver grains. The size and shape the the resulting grain is dependent on the combined characteristics of the film and the developer solution, development time, and temperature. ( Now you should understand why there are so many B&W Developers ) The shades of gray that you see in a negative are simply the result of variations in grain density, the more grains per unit area, the darker the region of the negative.

Chromogenic Color and B&W film operate a little differently, they still employ Silver Halide crystals to sense the light, but the emulsion also contains additional chemicals which eventually yield the final image:

This is a actual image of a Cyan layer after Color Development and now each grain is surrounded by a Cyan halo, or dye cloud, whose size and color density is proportional to the grain size and grain density. This is the result of the metallic Silver grain catalyzing the activation of the dye which then yields it's characteristic color, Cyan, Magenta, and Yellow for both chromogenic color negative and reversal transparency films, and Black for chromogenic B&W films.

The processing of chromogenic films doesn't stop here, once the dye cloud image is established, the film is then bleached to dissolve away the metallic Silver grain:

This is all you get from a chromogenic film, nebulous clouds of dye that fade away to the back ground transparency of the film and, correspondingly, the very character of the image is different from what you have if you used a traditional film yielding a Silver grain image.

Note: There is an accepted variation on color chromogenic film processing where the Bleach is cut short or skipped entirely, referred to as Bleach Bypass, yielding a deeper looking image comprising both the metallic Silver grain for image density and dye clouds for color.

Despite my "Un-Wanted" poster to introduce the subject, if you follow the B&H Photo links for each film, you'll see both are highly rated by a large number of photographers. Just keep in mind that it you intend on processing these yourself, you will need the C-41 color chemistry and it's temperature control requirements are far more stringent than traditional B&W, you if you are hoping for a nice grain, well, these films will not produce it.