Part One · The Explorer — Chapter 17

Quick Reference Tables and Chemistry Formulas

EV, Filters, Reciprocity, and Chemistry

Chapter brief: baseline standard and assistive themes

Film stock: ISO 400 Panchromatic (Tri-X / HP5+)
Developer: Kodak D-76 (1+1) @ 20°C
Paper: Fiber-Base (FB) Variable Contrast

Assistive themes

a fixed bench layout of haptic cues
graduated cylinder increments by touch
temperature compensation deltas
dilution ratios by count

Reading level: Explorer

Master Opening: The Guild Field & Wet Lab Reference

Every master craftsman needs an authoritative, instantly accessible bench ledger. In the field under shifting daylight, or in the darkroom under safelight, you should never have to guess a filter factor, miscalculate a dilution ratio, or extrapolate a temperature drift curve on the fly.

This final chapter of Part 1 serves as your Guild Field & Wet Lab Reference. It consolidates the quantitative foundations of The Silver Craft—from field exposure matrices and filter factor compensations to developer dilution math, temperature conversion tables, and archival washing protocols.

Keep these tables at hand. They are designed to streamline your workflow, enforce process control, and free your attention so you can focus entirely on the art of seeing.

Film stock: ISO 400 panchromatic film (Kodak Tri-X 400 / Ilford HP5+)
Developer: Kodak D-76 / Ilford ID-11 (diluted 1+1) @ 20°C (68°F)
Stop bath: Indicator stop bath (15–30 seconds @ 20°C)
Fixer: Rapid fixer (two-bath fixation @ 20°C)
Washing: Hypo-Clearing Agent (HCA) + running water wash
Paper: Multigrade Fiber-Base (FB) double-weight paper

1. Field Exposure & EV Reference Tables

Table 1.1: Exposure Value (EV at ISO 400) to Shutter/Aperture Combinations

Note: All values calibrated for ISO 400 film baseline.

EV (ISO 400)	Ambient Light Description	f/2.8	f/4	f/5.6	f/8	f/11	f/16
EV 17	Extreme glare — snow or sand at altitude	—	—	—	1/8000s	1/4000s	1/2000s
EV 16	Bright glare on snow or sand	—	—	1/8000s	1/4000s	1/2000s	1/1000s
EV 15	Sunny 16 baseline (bright day, distinct shadows)	—	1/8000s	1/4000s	1/2000s	1/1000s	1/500s
EV 14	Weak hazy sun, soft shadows	1/8000s	1/4000s	1/2000s	1/1000s	1/500s	1/250s
EV 13	Open shade / bright overcast	1/4000s	1/2000s	1/1000s	1/500s	1/250s	1/125s
EV 12	Heavy overcast / deep canopy shade	1/2000s	1/1000s	1/500s	1/250s	1/125s	1/60s
EV 10	Sunset / golden hour horizon	1/500s	1/250s	1/125s	1/60s	1/30s	1/15s
EV 8	Bright city streetlights / night art walk	1/125s	1/60s	1/30s	1/15s	1/8s	1/4s
EV 6	Interior home / tungsten ambient	1/30s	1/15s	1/8s	1/4s	1/2s	1s
EV 4	Nightscapes under streetlamp	1/8s	1/4s	1/2s	1s	2s	4s

Dashes mark combinations that would demand shutter speeds faster than 1/8000s — beyond most focal-plane shutters. Stop down toward f/16 or add a neutral-density filter instead.

Table 1.2: Optical Filter Compensation Matrix

Note: Exposure Factor indicates light reduction; Stop Compensation indicates stops to add to light meter reading.

Filter Type	Wratten #	Visual Primary Function	Exposure Factor	Stop Compensation	Metering Rule
Yellow	#8 (K2)	Natural sky contrast, subtle cloud pop	2×	+1.0 Stop	Open lens 1 stop or reduce shutter 1 step
Yellow-Green	#11 (X1)	The portrait filter — flatters skin, lightens foliage, gently darkens sky	4×	+2.0 Stops	Open lens 2 stops
Orange	#16	Dramatic sky contrast, cuts atmospheric haze	3×	+1.5 Stops	Open lens 1.5 stops
Red	#25	High drama, dark skies, wood grain separation	8×	+3.0 Stops	Open lens 3 full stops
Green	#58	Separates foliage tones, deepens sky; too harsh for portraits — darkens skin and emphasizes blemishes	6×	+2.5 Stops	Open lens 2.5 stops
Polarizer	Circular/Linear	Eliminates glare on non-metallic surfaces, darkens sky	2.5× to 4×	+1.3 to +2.0 Stops	Meter through filter or add 1.5–2 stops

Table 1.3: Reciprocity Failure Compensation (Long Exposures)

When exposure time exceeds 1 second, silver halide emulsions suffer from reciprocity law failure ( $H \neq I \times t$ ). Indicated exposure times must be lengthened to prevent severe underexposure in shadows.

Metered Indicated Time	Kodak Tri-X 400 Adjusted Time	Ilford HP5+ Adjusted Time	Reciprocity Exposure Adjustment
1 Second	2 Seconds	1.5 Seconds	Add +1.0 Stop
2 Seconds	5 Seconds	3.5 Seconds	Add +1.3 Stops
5 Seconds	15 Seconds	11 Seconds	Add +1.6 Stops
10 Seconds	35 Seconds	25 Seconds	Add +1.8 Stops
30 Seconds	130 Seconds (2m 10s)	85 Seconds (1m 25s)	Add +2.1 Stops
60 Seconds	300 Seconds (5m 00s)	180 Seconds (3m 00s)	Add +2.3 Stops

2. Darkroom Chemistry Formulas & Dilution Math

Table 2.1: Developer Preparation Math (D-76 / ID-11 Working Solution 1+1)

When working with stock developer diluted 1+1, combine equal parts stock solution and distilled water at 20°C (68°F). Never re-use diluted 1+1 working developer; discard after one tank cycle.

Tank Capacity / Format	Total Liquid Needed	D-76 Stock Volume	Distilled Water Volume
Single 35mm Roll (Paterson Tank)	300 mL	150 mL	150 mL
Two 35mm Rolls / One 120 Roll	500 mL	250 mL	250 mL
Four 35mm Rolls / Two 120 Rolls	1000 mL (1.0 L)	500 mL	500 mL
4×5 Sheet Film Tray (4 Sheets)	1000 mL (1.0 L)	500 mL	500 mL

Table 2.2: Chemistry Dilution Ratios & Tray Sequence

Wet lab tray sequence — left to right — Six print-processing stations, from paper developer through double fixer and optional selenium toner to the final running-water wash. Roll film is developed in a sealed daylight tank — never in an open tray.

Chemical Stage	Mixing Ratio	Stock Concentrate	Water Volume	Capacity / Shelf Life
Paper Developer	1+9 (Working)	100 mL concentrate	900 mL water	15–20 8×10 prints per liter tray
Indicator Stop Bath	1+63 (Working)	16 mL concentrate	984 mL water	Turns purple/blue when exhausted
Rapid Fixer (Film)	1+4 (Working)	200 mL concentrate	800 mL water	24 35mm rolls per liter
Rapid Fixer (Paper)	1+9 (Working)	100 mL concentrate	900 mL water	40 8×10 FB prints per liter
Hypo-Clearing Agent	1+4 (Stock to Work)	200 mL stock	800 mL water	50 8×10 FB prints per liter
Selenium Toner	1+19 (Protective)	50 mL toner concentrate	950 mL HCA solution	Discard after session

⚠️ SAFETY — Selenium Toner Requires Ventilation: Selenium compounds are toxic and can absorb through skin. Dilute and tone only under active ventilation (exhaust fan or open window — never in a sealed darkroom) and wear nitrile gloves. Never mix selenium toner with acidic baths, never heat or atomize it, and dispose of exhausted toner as hazardous waste — never down the drain.

Non-visual bench cue: selenium toner carries a sharp, metallic odor. A faint trace at arm’s length is expected; a strong smell at working distance means ventilation is insufficient. Stop, restore airflow, then resume.

3. Temperature Correction Curves (18°C to 24°C / 64°F to 75°F)

If darkroom ambient temperatures drift from the 20°C (68°F) standard, adjust development time according to Table 3.1 to maintain identical negative gamma and contrast.

Table 3.1: Developer Time Compensation Matrix (D-76 1+1)

Temperature (°C)	Temperature (°F)	Time Multiplier	Example Base Time (8.0 Min @ 20°C)
18.0°C	64.4°F	1.25×	10.0 Minutes
19.0°C	66.2°F	1.12×	9.0 Minutes
20.0°C (Standard)	68.0°F	1.00×	8.0 Minutes
21.0°C	69.8°F	0.89×	7.1 Minutes (7m 05s)
22.0°C	71.6°F	0.80×	6.4 Minutes (6m 25s)
23.0°C	73.4°F	0.71×	5.7 Minutes (5m 40s)
24.0°C	75.2°F	0.63×	5.0 Minutes

4. Zone System Development Adjustment Index ( $N \pm$ )

When field lighting contrast requires $N$ -development adjustments, alter D-76 1+1 development time at 20°C according to Table 4.1.

Table 4.1: $N$ -Development Time & Density Matrix

Development Code	Target Contrast Condition	D-76 1+1 Time Shift	Highlight Density Effect (Zone VII)
$N + 2$ (Expansion)	Flat overcast sky, extremely low scene dynamic range	+50% Time (12.0 Min)	Expands Zone V to Zone VII; snaps contrast
$N + 1$ (Expansion)	Soft open shade, low contrast scene	+25% Time (10.0 Min)	Expands Zone VI to Zone VII
$N$ (Normal)	Standard daylight lighting, 5-stop scene dynamic range	Base Time (8.0 Min)	Standard Zone VII highlight density
$N - 1$ (Contraction)	Bright sun, high contrast shadows	-20% Time (6.4 Min)	Compresses Zone VIII to Zone VII
$N - 2$ (Contraction)	Extreme harsh glare, deep canyon shadows	-35% Time (5.2 Min)	Compresses Zone IX to Zone VII; prevents clipping

5. Troubleshooting Diagnostic Checklist

Symptom	Diagnosis
Clear film celluloid (no image & no edge markings)	Fixer poured before developer, or unexposed film loaded wrong
Clear film celluloid (no image BUT crisp edge markings)	Camera shutter curtain failed to open, or lens cap left on
Wiped / dense fogged film (solid black throughout)	Accidental daylight exposure, or shutter curtain stuck wide open
Thin negatives (faint shadows & pale highlights)	Severe underexposure in field — check light meter ISO dial
Dense blocked highlights (chalky highlights on print)	Overdevelopment in tank — excessive time, temperature, or agitation
Spurious white spots on print	Dust on negative or glass carrier during enlarger exposure

6. Assistive Haptics & Accessible Lab Reference

For blind and low-vision photographers, wet lab precision relies on structured spatial layout, haptic cues, and acoustic confirmation.

Bottle shape coding: Developer lives in a round amber glass bottle with a smooth neck; stop bath in a square HDPE plastic bottle with a ribbed neck; fixer in a triangular / fluted plastic bottle with a double neck ring.
Tactile measuring graduates: Use raised silicone bump-dots or Braille bands on graduate cylinders at the 150 mL, 250 mL, and 500 mL marks.
Thermal audition: Use a talking digital probe thermometer or haptic notch ring to confirm the 20°C water bath temperature without visual sight.

Part 1 Concluding Handoff

With this chapter, you hold the complete Explorer’s Field and Darkroom Guide. You have traveled from the history of silver halides and Group f/64 to field exposure metering, darkroom chemistry, print performance, and archival preservation.

The tools are calibrated. The baseline is established. The darkroom door is closed.

Step into the light and begin Part 2: The Assayist’s Technical Reference.