darktable preset inspired by KentmerePan 400

What the style changes

The style converts the photo to black and white as a panchromatic ISO 400 film would, then adds soft contrast and visible grain. What it is based on is on the Kentmere Pan 400 film page. All figures below come from renders made at 1000 px with tools/validate.py, measured in CIELab, and compared with darktable’s base rendering and with the HP5 Plus and Tri-X styles.

• Gray from assumed channel weights. A color calibration instance named “N&B” mixes the channels with weights halfway between those of the Tri-X and HP5 Plus styles. Harman’s datasheet publishes no spectral sensitivity curve, so this is an assumption backed by reviews, not by measurements.
  • Against the base rendering, the sky gets lighter (L 55.3 → 59.2) and skin darker (78.2 → 75.0), as with any panchromatic film. The shift is smaller than in the HP5 Plus style (sky 60.6), which is expected since the weights are an assumption. Take it with caution.
• Soft contrast. The tone curve has a near-neutral slope. Global contrast is the lowest of the three black-and-white styles compared: Lsd 29.6 against 30.6 for HP5 Plus and 33.5 for Tri-X on photo 1014 (base 30.7).
• Lifted blacks and held-back whites. Reviews call the film “flat” and “muddy”. The style follows: L5 rises from 2.6 to 3.0 and L95 falls from 87.9 to 85.6. In a complementary one-off measurement, 0.3 % of pixels are near black (5/255 or below) on photo 1014, against 3.6 % for HP5 Plus and 16.0 % for Tri-X (base 1.7 %). The shadowed wall on photo 1013 stays at the base level (L 6.0 against 6.3).
• Visible grain. Coarseness 2400 and strength 29, against 2200 and 26 for the HP5 Plus style. The high-pass standard deviation on the top third of photo 0775 is 3.71, against 0.46 for the base, 3.16 for HP5 Plus and 3.77 for Tri-X.
• A truly neutral gray. Chroma falls from 8.6 to 0.0: no color cast is left.

What it leaves alone

• Your base development. The style contains no exposure, no sigmoid or filmic and no LUT. Those settings stay as you made them.

• But it switches off your main color calibration. The style contains two color calibration instances:

  • a disabled one with no instance name, which replaces your main color calibration and switches it off. It is set to “as shot in camera” with CAT16, like darktable’s default, so you can switch it back on;
  • the “N&B” instance, which does the black-and-white conversion.

  Why: when an active color calibration runs after the black-and-white conversion, its chromatic adaptation tints the gray. The disabled instance avoids that.

• It also replaces your tone curve and grain. The style’s tone curve and grain carry no instance name, so they replace any settings you had already made in those two modules. Your earlier settings remain in the history.

• Your pipeline order. The style file carries no module order list.

Details on applying a style: Install and apply darktable styles.

Limits

• An interpretation, not a calibration. No film was scanned or measured to tune the style.
• No spectral or characteristic curve. Harman’s datasheet (4 pages) publishes neither a spectral sensitivity curve, nor a characteristic curve, nor a granularity figure. The channel weights and the tone curve are assumptions supported by reviews, not by measurements.
• Reviews are subjective and disagree on grain, some calling it fine, others pronounced. The grain setting is the most uncertain part. If it looks too strong, lower the strength toward 24.
• The rendering varies with the developer and the exposure. The style aims at normal development at EI 400.
• Lifted blacks come from reviewers’ words (“flat”, “muddy”). If you want solid blacks, bring the first node of the tone curve back to (0, 0).
• The grain. darktable’s grain is procedural noise: it imitates the texture of film grain, not the shape of real silver grains.
• The measurements come from a few test photos of our own. They are not published on this site.

Tips

• Apply it early. If you plan to fine-tune the tone curve or grain yourself, apply the style first: it would replace those settings if you made them before.
• Solid blacks: set the first node of the tone curve to (0, 0).
• Back to color: switch the main color calibration back on and switch off the “N&B” instance.
• Installation: see Install and apply darktable styles.