Assignment: Portrait, Environmental Portrait and Self-Portrait

The intention

Make three negatives of a person — a head-and-shoulders portrait, an environmental portrait at a short focal distance, and a self-portrait — in which the exposure time was chosen by asking what a human being can hold, and everything else in the camera was then solved backwards to fit it.

Every assignment so far has computed a time. This one starts from the time and computes the aperture, because the sitter is the only component in the system with an opinion. That inversion is one line of algebra, and it changes which pinhole plate goes in the camera, how sharp the picture can be, and whether the eyes survive.

Learning objectives

By the end of this session you should be able to:

• Solve the exposure relation for the f-number given a hold time you have agreed with a person, and say what that choice of hole costs in blur.
• Predict where a sitter will move first, and why the eyes go before the hands and the hands before the shoulders.
• Predict the tonal rendering of skin, lips, hair and any redness on a blue-sensitive paper negative against a panchromatic film, and attribute each difference to spectral sensitivity rather than to taste.
• Plan a self-portrait as a timetable, with the presence fraction computed before you walk into the frame.
• State the conditions under which this course photographs a person, and hold to them.

Prerequisites

Time in the Frame owns the presence fraction and the smear geometry that the self-portrait and the moving sitter both use, and this page applies them without re-deriving them. Still Life and Controlled Light owns the indoor exposure arithmetic and the fact that a pinhole has no separate bellows factor. Part IV’s spectral sensitivity lesson owns why a blue-sensitive material renders a face the way it does. Part VI’s exposure and reciprocity lesson owns the relation everything here is rearranged from.

Safety classification

Level A. No new chemistry, and the same three baths as the previous three assignments. What is new is that the subject is a person, which introduces obligations rather than hazards.

• Substances. Paper developer, stop and rapid fixer at working dilution, indoors, as before.
• Energies. Daylight, and a long outdoor session if you work in the open. No lamp on this page is brought close to a sitter.
• Procedures. A person holding a position for tens of seconds, unsupported by anything that restrains them.
• Waste. Used fixer is silver-bearing and is collected.

What is not a hazard here, and why. Nothing in this session is done to the sitter. The camera emits nothing: it is a light-tight box with a hole in it, and the exposure is the sitter sitting still while nothing happens. There is no flash, no continuous lamp near the face, no chemistry within reach of them, and no equipment they touch. The one physical risk in the whole assignment is the ordinary discomfort of holding a position, which is why the controls below are about breaks, support and consent rather than about protection. Naming that plainly matters, because a page that said nothing about hazards to a sitter would read as though nobody had thought about them.

Hazards

Sitter comfort, stated as conditions rather than as guidance from an authority. No head clamp, no brace, no strap and no restraint of any kind is used in this course, ever. A chair with a back, a wall, a table edge or a door frame is the whole of the permitted support, and the sitter chooses whether to use it. Every exposure is followed by a break in which they move. If a sitter says they have had enough, the session is over; there is no negative worth the sentence “just one more”.

Consent and comfort. Ask before you photograph, say how long the exposure will be, say what the picture is for, and say that they can stop. For a person who cannot consent for themselves — a child, most obviously — ask the person responsible for them, in their presence, and take a refusal from either as final. Article 2(2)(a) of the UK GDPR puts a student’s own photographs, made for their own study, outside the Regulation as “a purely personal or household activity”; that is the law’s answer and it is not the whole answer, because it tells you what you may do and not what you should. Publishing, exhibiting or submitting the picture anywhere is a second and separate conversation.

Sun. If you work outdoors in the middle of the day, ICNIRP’s shadow rule applies to you and to the sitter alike: a shadow shorter than you means the ultraviolet is at its strongest, which under clear skies in late spring and summer is the four hours around midday. A sitter asked to hold still in direct sun for ninety seconds is a sitter you have put in the sun on purpose.

Indoors, afterwards. The developer is a skin sensitiser and the fixer is an irritant; the controls are the ones Part II established and Part VII has used on every practical page since.

Required PPE

• Nitrile gloves, eye protection and one pair of tongs per tray for the processing half of the session, which is the only half with chemistry in it.
• Sun protection for both of you — hat, sleeves, sun cream and shade between sheets — if the making half is outdoors in the middle of the day. On this page that is protective equipment for a second person as well as for yourself, which is a new responsibility.

Ventilation

Not among the outdoor controls. Indoors, an openable window or an extractor rather than a sealed cupboard, which is ILFORD’s general instruction for darkroom work; none of the three baths at these dilutions generates a vapour that calls for extraction.

Materials

Item	Quantity	Notes
Variable-contrast RC paper	12 sheets	Nine planned, three spare.
Panchromatic sheet film	2 sheets	Optional, for the material comparison. Process by the owning lesson.
A person who has agreed to sit	1	Read the consent conditions before you ask.
A chair with a back	1	The only support this course uses.
White card, about A2, for a reflector	1	Kitchen foil crumpled and flattened on card is the harder-edged alternative.
A watch with a second hand	1	The sitter can see it. This matters more than it sounds.
Prediction sheet, folded	3	Predictions on the left, observations on the right.

Chemicals

Chemical	Quantity	Form
Paper developer concentrate	100 mL	Diluted 1+9 to make 1 L; 60 seconds at 20 °C for RC paper.
Stop bath concentrate	50 mL	Diluted 1+19 to make 1 L; about 10 seconds. A citric acid stop.
Rapid fixer concentrate	200 mL	Diluted 1+4 to make 1 L; 30 seconds for RC paper. An ammonium thiosulfate fixer.
Water	about 12 L	Dilution and washing.

Equipment

The camera at two of its three focal distances — 50 mm for the close head and for the environmental portrait, 120 mm for the flatter head if the light will carry it; at least three pinhole plates of different measured diameters, including the largest you own, because the aperture is the variable this page solves for; the pinhole register; a tripod; a lux meter or a phone app calibrated once in bright sun as Part VI describes; a timer; and the processing kit from the previous sessions.

Estimated cost

Cost band £. Twelve sheets of paper, two of film if you take the comparison, and a session’s chemistry. Dated prices live in the laboratory planner.

Waste streams

Used fixer is silver-bearing, and so is the first change of wash water; both go into the labelled collection container rather than to the drain. Used developer and stop carry no silver. Local regulations govern where the container goes next.

Preparation

1. The sitter sets the time, so the camera must supply the aperture

Part VI’s relation, in the form the still-life page used, gives the time from everything else:

t = N² C / (E S)

Time from illuminance

t is the exposure in seconds, N the effective f-number, E the illuminance in lux at the sitter, S the effective ISO of the material and C ≈ 310 the incident constant Part VI derived. Rearranged for the aperture, it answers the only question a portrait actually asks:

N = √( t E S / C )

The f-number that fits a hold time

Read it as an instruction. Agree a hold time with the person in front of you. Measure the light. Then compute the f-number that lands the exposure on that time, and fit the plate closest to it. The hole you end up with will usually be larger than the optimum Part VI computed, and the picture will be correspondingly softer, and that is a decision rather than an accident.

🧮DO THE MATHS: a thirty-second portrait, and what it costs in sharpness

The scene. Outdoors, cloudy bright, the sitter against a wall in open shade. The meter at the face reads 24,800 lux, which is the illuminance Kodak’s “cloudy bright” daylight row implies when Part VI’s constant is run backwards through it. Paper at ISO 3. You and the sitter have agreed on 30 seconds, which is long enough to be difficult and short enough to be possible.

N = √(30 × 24,800 × 3 / 310) = √(7,200) = f/85

At the camera’s short setting, f = 50 mm, f/85 means a hole of 50/85 = 0.59 mm, and the 0.60 mm plate from Part VI’s reference set is f/83 — near enough that you can fit it and recompute rather than the other way round. At f/83 the exposure is 83² × 310 / (24,800 × 3) = 29 seconds.

What it costs. Part VI’s optimum at 50 mm is 0.26 mm, so this is a hole more than twice the optimum diameter. The geometric blur is d(1 + f/u), which for a sitter at 0.4 m is 0.60 × 1.125 = 0.675 mm. At 0.4 m the 127 mm sheet takes in 1.02 m of scene, so an eye 25 mm wide in life is 3.1 mm on the negative and the blur is 22 per cent of it. You will get an eye. You will not get an eyelash, and the iris will not have an edge.

The alternative is the long setting and better light. At f = 120 mm the same 0.60 mm plate is f/200, and f/200 needs 167 seconds in this light — no. Move the sitter into direct sun at 100,000 lux and the same f/200 comes down to 41 seconds, with a blur of 0.69 mm but a flatter, more conventional head, because at 0.8 m rather than 0.4 m the nose is no longer half a focal distance nearer the hole than the ears. Sharpness, framing and hold time are three corners of one triangle, and the light decides how big the triangle is.

The f-number that lands the exposure on a chosen hold time, on ISO 3 paper

• 100,000 lux — direct sun on the face
• 24,800 lux — cloudy bright, open shade
• 12,150 lux — heavy overcast or deep shade
• 5,000 lux — bright indoor position

Show the numbers behind this plot

Four rising curves of the required effective f-number against the hold time agreed with the sitter, computed for a material at ISO three from the relation N equals the square root of time times illuminance times speed divided by three hundred and ten. Each curve is a square root, so it rises steeply at first and then flattens: quadrupling the hold time only doubles the f-number. The lowest curve is for a bright indoor position at five thousand lux, where ten seconds needs f slash twenty-two, thirty seconds f slash thirty-eight, sixty seconds f slash fifty-four, one hundred and twenty seconds f slash seventy-six and one hundred and eighty seconds f slash ninety-three. Next up is heavy overcast or deep shade at twelve thousand one hundred and fifty lux, where the same five times give f slash thirty-four, f slash fifty-nine, f slash eighty-four, f slash one hundred and nineteen and f slash one hundred and forty-six. Above that is cloudy bright at twenty-four thousand eight hundred lux, giving f slash forty-nine, f slash eighty-five, f slash one hundred and twenty, f slash one hundred and seventy and f slash two hundred and eight. The uppermost curve is direct sun at one hundred thousand lux, giving f slash ninety-eight, f slash one hundred and seventy, f slash two hundred and forty-one, f slash three hundred and forty-one and f slash four hundred and seventeen. A shaded horizontal band from f slash two hundred to f slash three hundred marks the f-numbers the camera's near-optimum plates give at its three focal distances of fifty, eighty and one hundred and twenty millimetres, and the practical lesson is where each curve crosses that band. Only the direct-sun curve crosses it inside a holdable time, at about forty seconds for f slash two hundred and ninety seconds for f slash three hundred. The cloudy-bright curve does not reach f slash two hundred until nearly three minutes, and the indoor curve never reaches the band at all within the plotted range, which is why an indoor portrait on paper is made with an oversized hole, or is not made.

Series	Hold time agreed with the sitter, seconds	Effective f-number required
100,000 lux — direct sun on the face	5.00	69.00
100,000 lux — direct sun on the face	10.00	98.00
100,000 lux — direct sun on the face	20.00	139.00
100,000 lux — direct sun on the face	30.00	170.00
100,000 lux — direct sun on the face	45.00	208.00
100,000 lux — direct sun on the face	60.00	241.00
100,000 lux — direct sun on the face	90.00	295.00
100,000 lux — direct sun on the face	120.00	341.00
100,000 lux — direct sun on the face	180.00	417.00
24,800 lux — cloudy bright, open shade	5.00	35.00
24,800 lux — cloudy bright, open shade	10.00	49.00
24,800 lux — cloudy bright, open shade	20.00	69.00
24,800 lux — cloudy bright, open shade	30.00	85.00
24,800 lux — cloudy bright, open shade	45.00	104.00
24,800 lux — cloudy bright, open shade	60.00	120.00
24,800 lux — cloudy bright, open shade	90.00	147.00
24,800 lux — cloudy bright, open shade	120.00	170.00
24,800 lux — cloudy bright, open shade	180.00	208.00
12,150 lux — heavy overcast or deep shade	5.00	24.00
12,150 lux — heavy overcast or deep shade	10.00	34.00
12,150 lux — heavy overcast or deep shade	20.00	49.00
12,150 lux — heavy overcast or deep shade	30.00	59.00
12,150 lux — heavy overcast or deep shade	45.00	73.00
12,150 lux — heavy overcast or deep shade	60.00	84.00
12,150 lux — heavy overcast or deep shade	90.00	103.00
12,150 lux — heavy overcast or deep shade	120.00	119.00
12,150 lux — heavy overcast or deep shade	180.00	146.00
5,000 lux — bright indoor position	5.00	16.00
5,000 lux — bright indoor position	10.00	22.00
5,000 lux — bright indoor position	20.00	31.00
5,000 lux — bright indoor position	30.00	38.00
5,000 lux — bright indoor position	45.00	47.00
5,000 lux — bright indoor position	60.00	54.00
5,000 lux — bright indoor position	90.00	66.00
5,000 lux — bright indoor position	120.00	76.00
5,000 lux — bright indoor position	180.00	93.00

Computed from N = √(tES/C) with C = 310 and S = 3; nothing here is measured, and no reciprocity correction is carried, because none is published for paper. Read it before the sitter arrives: it tells you which plate to fit, and whether the light you have will let you use a good one. The curve is drawn to show the shape, not measured from a real material. Your own materials will differ, and measuring them is what the sensitometry part of the course is for.

Film changes the shape of the problem rather than the size of it. ILFORD rate HP5 PLUS at ISO 400/27°, which is over seven stops faster than paper taken at ISO 3. At the same cloudy-bright 24,800 lux and the near-optimum f/200, the metered time is 1.25 seconds — and ILFORD’s reciprocity sheet states that exposures of one second or less need no compensation, so the correction here is small and the arithmetic is nearly honest as it stands. On film a portrait is an ordinary photograph; on paper it is a nineteenth-century one. Choosing between them is choosing which century’s problem you want.

2. What moves first, and why

A person holding still is not still. Three things move, on three different timescales, and knowing the order lets you predict what the negative will show.

The eyes go first. They saccade continuously, and blinking is involuntary. Over ten seconds an eye is in several places; over sixty it has blinked ten or more times. On the negative the iris and pupil average with the eyelid and the white, which is why a long-exposure portrait so often has soft, dark, indeterminate eyes even when the face is crisp.

Hands go second. They are the far end of a long unsupported lever and they drift. Hands in a lap, or wrapped around a mug, or holding each other, move far less than hands resting on a chair arm.

The head and shoulders go last, and only if unsupported. A back against a chair and a chin with somewhere to be are worth more than any instruction.

Part VII’s movement page gives the smear arithmetic: the image displacement is the subject displacement times the magnification, and the magnification here is f/u. The head-and-shoulders portrait is the unforgiving case, because it is made close. At f = 50 mm and a sitter at 0.4 m the magnification is 1/8, so a hand that wanders 5 mm smears 0.63 mm — already the size of the blur circle. Back off to the environmental framing at 1.2 m and the magnification falls to 1/24, so the same 5 mm costs only 0.21 mm and a 15 mm drift is needed before it matters.

That is the number to give the sitter, because “hold still” is not an instruction anybody can follow and “your hands can move about the width of a fingernail while I am this close, and about the width of a thumb when I move back” is.

🕰The exposure you are about to give is the one the trade spent twenty years escaping

The Library of Congress’s account of the daguerreotype states that “exposure times for the earliest daguerreotypes ranged from three to fifteen minutes, making the process nearly impractical for portraiture”, and that changes to sensitisation together with better lenses “soon reduced the exposure time to less than a minute”.

Your computed portrait exposure — thirty to ninety seconds on paper in good light — lands inside the band the trade reached after those improvements — and you are getting there with a hole in a piece of shim rather than with a fast portrait lens, because your material is many stops faster than a daguerreotype plate. The two effects have very nearly cancelled. What you are doing is not a re-enactment; it is the same arithmetic run with a slow aperture and a fast material instead of a fast aperture and a slow one, and it is worth knowing that this is why your portrait exposure feels historical.

⁇The head rest: two named positions, and why this course takes neither at face value

Whether a sitter should be held in place was argued in print, and the two sides are worth reading because neither is arguing about physics.

P. H. Emerson, 1889. In Naturalistic Photography he is categorical: “Head-rests must be entirely tabooed.” His grounds are aesthetic and experiential together — “We have taken many portraits, some with very long exposures, and no head-rest was necessary. In nine cases out of ten it simply ruins the portrait from an artistic point of view” — and elsewhere he calls posing with head rests “feeble and archaic, and certain to result in failure”.

E. J. Wall, 1912. The Dictionary of Photography defines the head rest as “an apparatus used for maintaining an exact position and steadiness of a sitter during exposure”, concedes that “great prejudice exists in the minds of most people against it, due to its use having been abused to such an extent as to become an absolute instrument of torture”, and then defends a disciplined version: “In all cases the head-rest should be adapted to the position of the sitter’s head and applied gently, and the head should never be strained to the position of the head-rest.”

What this course does, and why. It uses no restraint of any kind, and its reason is neither Emerson’s nor Wall’s. Emerson’s objection is to how the resulting pictures look; Wall’s defence is that the apparatus can be used considerately. The course’s rule is simply that a student is not a professional studio and a friend is not a client, and that an unfamiliar person applying a clamp to another person’s head is a bad arrangement whatever the picture looks like. A chair, a wall and a shorter exposure do the same work. Note that this is a decision about conduct, and that the two period authorities are quoted here to show that it was argued about, not to settle it.

3. Skin, on two materials, predicted before it is seen

Part IV establishes the mechanism and this page only applies it. An undyed silver halide emulsion — which is what ordinary enlarging paper is — responds in the blue and the ultraviolet and stops around 500 nm, so anything that reflects mainly red light reflects light the paper cannot use, and records as though it were in shadow. ILFORD say the same thing about a current film: ORTHO Plus has no red sensitivity, so “reds appear much darker than normal”, and they offer it as an effect.

The consequences for a face follow directly, and they are the prediction you write down.

Predicted tonal order of a face on a blue-sensitive paper negative and on panchromatic film

1. 1Blue-sensitive paper — responds below about 500 nm; reds record as shadow, blues record as highlight
2. 2Panchromatic film — responds across the visible; the face keeps the tonal order the eye expects
3. 3The two reversals — red features fall on paper and rise on film; blue features do the opposite

Predicted from the spectral sensitivities Part IV establishes, not measured from negatives. Write your own version of this ladder for your sitter before you expose, then rank the developed negative against it.

The practical instruction that falls out of it. If your sitter has red or auburn hair, freckles, a flush, rosacea, acne, or is wearing lipstick, paper will exaggerate every one of those and film will not, and you should say so before you photograph them rather than after. Some sitters will want the paper rendering, which is severe and archaic and can be very beautiful. Some will not. Asking is part of the assignment.

4. Light for a face, and one card

North window light is the traditional portrait light because it is large, soft and nearly constant. The still-life page’s table says what it costs: at 5,000 lux close to a bright window, paper at ISO 3 needs 827 seconds at f/200. Fourteen minutes is not a portrait, so indoors you have three moves and you should make all three: work as close to the window as the framing allows, fit the largest hole you own, and accept the softness. If that still lands past two minutes, go outside.

The reflector earns its place by arithmetic, not by convention. Paper as a negative has a short scale — ILFORD’s own ISO Range figure for MULTIGRADE RC is the evidence, and the still-life page works through what it means — so the difference between the lit and the shadowed side of a face is the whole tonal problem. A white card held on the shadow side at about the sitter’s own distance from the window lifts that side by something you can measure with the meter in two readings, and that measured difference, in stops, is the number to log, not the word “reflector”.

Window-light portrait plan, with the framing geometry at each camera setting

1. 1Window — the light source; measure the lux at the face, not at the window
2. 2Sitter, three-quarters to the light — back against the chair; hands occupied; a fixed point to look at
3. 3Reflector card on the shadow side — log the lit-to-shadow difference in stops, measured, before and after
4. 4f = 50 mm at 0.4 m — the close head — field 127 × 400/50 = 1.02 m; magnification 1/8, so near-far stretch and smear are both at their worst
5. 5f = 50 mm at 1.2 m — the environmental portrait — field 3.05 m; same f-number, same exposure, one quarter of the smear
6. 6f = 120 mm at 0.8 m — the flat head, in sun only — field 0.85 m; f-number 2.4 times higher, so the exposure is 5.76 times longer — 2.53 stops

Field width = sheet width × subject distance ÷ focal distance, which is Part VI's similar-triangles result rearranged. Compute all three framings before the sitter arrives; adjusting the framing with a person waiting is what uses up their patience.

5. The self-portrait, written as a timetable

A self-portrait with a pinhole is a scheduling problem. There is no shutter release you can reach and no way to check the framing while you are in it, so you plan the exposure as a sequence of timed events and then execute it against a watch.

The tone you will record is given by the presence fraction the movement page derived. If you occupy your patch of the frame for a fraction φ of the exposure, and your luminance relative to the background behind you is r, the patch receives φr + (1 − φ) times what the bare background would have delivered.

🧮DO THE MATHS: a ninety-second self-portrait with a forty-second hold

The plan. Total exposure 90 s. You open the shutter, walk into the frame, hold for 40 s, walk out, and close. φ = 40/90 = 0.444.

A dark subject against a lighter ground, r = 0.2 — a person in dark clothes against a sunlit wall. The patch receives 0.444 × 0.2 + 0.556 = 0.644 of the bare-background exposure, which is −0.63 stop. That is a distinct but transparent figure: you will read as present, and the wall will read through you.

A mid-toned subject, r = 0.5, gives 0.778, which is −0.36 stop — near the limit of what a paper negative resolves. If your prediction was “half a person” you will get a smudge.

To record solid you must occupy nearly the whole exposure. At φ = 0.9 with r = 0.2 the patch is 1.84 stops down; at φ = 1 it is 2.32. The last tenth of the exposure is worth more than the first half, because the arithmetic is logarithmic while the light adds linearly. A solid self-portrait is therefore a hold of eighty seconds out of ninety, not forty, and the walk in and the walk out have to come out of the ends of the exposure rather than the middle of it.

A ninety-second self-portrait, planned as events against a watch

Shutter

open — 90 s

You

walk in, 5 shold — 80 s, φ = 0.89out

Alternative

gap 25 shold 40 s, φ = 0.44 — a ghostgap 25 s

0 s45 s90 s

The two rows are the same exposure with two different intentions. The upper plan makes a solid figure and gives you five seconds at each end to move; the lower makes a transparent one on purpose. Write which you intended in the log before the shutter opens, because afterwards the negative looks like whichever one you got.

Two practical points the arithmetic does not give you. Focus is not one of them — a pinhole has none, so you cannot be out of focus, only outside the frame. Mark the spot you will stand on with a stone, a coat or a chalk line, and check it with the angle-of-view template from the previsualisation lesson rather than by guessing. And keep the walk in and the walk out out of the frame’s edge, or you will record two faint additional figures.

6. Write the predictions, then fold the sheet

Before the first exposure, on the prediction side of the folded sheet: the agreed hold time; the measured lux at the face; the computed f-number and the plate you actually fitted; the resulting blur in millimetres and what fraction of the eye it is; the tonal ladder for this sitter’s face; the lit-to-shadow difference in stops with and without the reflector; and, for the self-portrait, φ, r and the predicted change in stops. Fold it over. You do not see it again until the negatives are dry.

The making

Stage 1 — Set up before the sitter arrives (25 minutes)

Place the chair, measure the light at the position the face will occupy, compute the f-number, fit the plate, set the tripod at the sitter’s eye height and frame on a coat draped over the chair. Every minute spent here is a minute the sitter does not spend waiting. Log the plate, the measured f, the measured lux and the computed time before anyone sits down.

Stage 2 — The head and shoulders, and its bracket (30 minutes)

Sit them down, tell them the exposure length, show them the watch, and agree the hold. Expose three sheets: the computed time, and one stop either side, obtained by changing the time and not the plate, so that the blur is the same on all three. Between sheets, they move. Log what moved during each exposure, from watching them rather than from guessing.

Stage 3 — The environmental portrait (25 minutes)

Stay at f = 50 mm, move back to about 1.2 m, and reframe: the 127 mm sheet now takes in 3.05 m of the scene, so the room arrives with the sitter. The exposure does not change — the f-number has not changed and a pinhole has no bellows factor — which is worth noticing, because a lens photographer moving from 0.4 m to 1.2 m would have changed two things and you have changed one. Frame so that the room does real work — a doorway, a window, a table with something on it — and place the sitter off the centre line, where the near-far stretch is strongest. Two sheets.

Stage 4 — The self-portrait (25 minutes)

Execute the timetable. One sheet to the solid plan, one to the ghost plan if you have paper left, and the watch times both. If you have a second person present, they do not touch the camera; they hold the watch and say “in” and “out”, which is the whole of their job.

Stage 5 — Process everything together (30 minutes)

Developer 1+9 for 60 seconds at 20 °C, stop about 10 seconds, rapid fixer 1+4 for 30 seconds, wash. All eight or nine sheets in one session at one temperature, so that processing is not a variable between them.

Stage 6 — Rank, then unfold the predictions (15 minutes)

Rank the developed negatives’ features against your written ladder before you unfold the prediction sheet, then unfold it and compare. Ranking first is the control for the fact that a prediction you have just read is very easy to see.

Expected observations

On the head-and-shoulders sheets. Eyes softer and darker than the rest of the face on every sheet, more so on the longer bracket. Hands, if unsupported, visibly smeared where the face is not. The whole picture uniformly soft at the scale of the hole you fitted — not soft in some places and sharp in others, which is the fingerprint that distinguishes a pinhole portrait from a badly focused lens portrait.

On the paper’s rendering of the face. Lips very dark. Any redness exaggerated. Blue clothing and a blue-painted wall much lighter than they look. If your sitter has red hair, expect it to read black, and expect that to be the single most surprising thing on the sheet.

On the environmental sheet. The sitter’s near hand or knee much larger than a lens photograph would render it, and the room’s far corners noticeably darker: at f = 50 mm on a 4 × 5 sheet the corner sits 58.4° off axis, which the cosine-fourth law puts 3.73 stops down before any plate-thickness effect is counted, and Part VI’s table is where that number comes from.

On the self-portrait. Whatever fraction you actually held, rather than the one you planned. Most first attempts are held for less time than intended, because standing still while counting is harder than sitting still while somebody else counts.

Evaluation and reconciliation

Answer these in the log, in numbers wherever a number exists.

1. Did the exposure land? Compare the sheet you judge correct against the computed time. The ratio is a measurement of your paper’s effective speed at this light level, and it goes into the collation the portfolio review will do.
2. Was the blur the size you predicted? Measure the softest edge you can find on the negative — the edge of a collar against a plain ground is the easiest — and compare with the hole diameter you fitted. They should agree to within the width of your rule.
3. Where did motion occur, and how much? Identify each smeared feature, estimate the smear in millimetres on the negative, divide by the magnification f/u, and state how far that part of the sitter actually moved. Then say whether a support, a shorter hold or a different pose would have fixed it.
4. Did the tonal ladder hold? Rank the features on the negative and compare with your written order. Every inversion is either a mistake in the prediction or something about this sitter’s colouring you did not account for, and both are worth a sentence.
5. What was the presence fraction you achieved? From the self-portrait’s density relative to the background, invert φr + (1 − φ) and compare with the φ you planned.

The critique

One paragraph per selected picture, and it names causes rather than preferences. Answer, in order: what was the intention as written; which optical fact produced the look; whether the exposure was right and by how much; whether the tonal rendering matched the prediction; what moved and whether it helped; and what single change you would make next time. A critique that says a picture is “atmospheric” has said nothing; a critique that says “the eyes are dark because a forty-second exposure averages ten blinks, and I would light the face from higher to keep the lids off the iris” has said something you can act on.

One further question, which belongs only to this page. Say whether the sitter would recognise themselves in the picture, and whether that matters to what you were trying to do. A portrait is the one assignment in this part whose subject has a view.

Troubleshooting

What you see	Most likely cause	What to check, and what to change
The whole face soft, evenly, at every distance	The hole you fitted to buy a short exposure	Measure the blur against the hole diameter; if they agree, this is the trade you chose, not a fault
The face sharp but the eyes dark and indistinct	Blinking and saccades averaged over the exposure	Shorten the hold with a larger hole, or accept it; there is no posing fix for a blink
One side of the face empty and the other blocked	Subject brightness range beyond paper’s short scale	Measure both sides in lux; if the difference is over about three stops, the reflector was too far away or too small
The sitter recorded as a faint transparency	The hold was shorter than planned	Recompute φ from the density and compare with the timetable; the watch is the fix
Lips and freckles far darker than expected	Blue-sensitive paper doing what Part IV says it does	Not a fault. Repeat on panchromatic film to see the other rendering
A second faint figure at the frame edge	You walked through the frame after opening the shutter	Plan the walk-in outside the field; the template shows where the field ends

Clean-up, storage and disposal considerations

Rinse the trays and tongs; return unused paper to its bag and box. Dry the negatives face up on a clean surface and sleeve them the same day, labelled to the log entry, in the enclosures the portfolio review specifies.

Used fixer is silver-bearing. It is collected with the first change of wash water into the labelled container Part II established, and it is not poured away. The reason is chemistry rather than regulation — silver in a thiosulfate complex is a soluble metal load rather than an inert one — and local regulations govern the route your container eventually takes. Developer and stop at these dilutions are handled by the same route the earlier practical pages set out.

What to submit

• One portrait — head and shoulders or environmental, your choice — as negative and working positive.
• One self-portrait, as negative and working positive.
• The log entries for every sheet exposed, including the ones you rejected, with the ten before-the-shutter fields filled in first.
• The folded prediction sheet, unfolded, with the observations written beside the predictions.
• Two critique paragraphs, one per submitted picture, in the form above.
• A sentence recording the sitter’s consent: who they are to you, what they were told, and what they agreed the picture could be used for.

Further work

The sitting-time series. Photograph one sitter at 10, 30, 90 and 180 seconds, changing the plate each time so the exposure is constant, and mount the four together. It is a direct measurement of where the human limit is for that person, and it is the number that decides every future portrait you make with this camera.

The two-material pair. The same sitter, the same light, the same framing, on paper and on panchromatic sheet film. Nothing else in this part shows the effect of spectral sensitivity as plainly, because a face contains blue, green and red in an arrangement everybody already knows by heart.

The group problem. Two sitters at once doubles the chance that somebody moves, and the presence arithmetic says the picture will show it. Predict, before you expose, which of the two will be the sharper, and why.