All twenty-two entries

Every entry is one process or step, what it demands, and the look that follows. The homepage carries a selection; this page carries everything, in section order.

• 01The daguerreotypeA mirror-surfaced silver plate with terrifying detail and no negative, so no copies existed — and Daguerre's 1838 Boulevard du Temple caught a man having his boots blacked, the first photograph of a person, only because he stood still.
• 02The calotypeHenry Fox Talbot gave up sharpness and got the negative, and therefore the copy.
• 03Niépce at Le GrasBitumen of Judea on pewter needed most of a day, which is why the sun appears to light both sides of the courtyard.

• 01CollodionFrederick Scott Archer's 1851 process had to be coated, exposed and developed while wet, which is why the darkroom went into a cart.
• 02The field darkroomA tent, a cart or a converted wagon, and the working radius that a wet plate allows.
• 03The wet-plate lookUneven pour, bromide drag and edge artefacts as evidence of a hand rather than faults.

• 01What moves disappearsLong exposures empty a street of everything except what stays still, which is why early city views look depopulated.
• 02Stopping downAperture buys depth of field and costs light, and the trade is the whole of practical exposure.
• 03Reciprocity failureAt long exposures the film stops obeying the arithmetic.

• 01Trays and safelightDeveloper, stop, fix, wash — a sequence, a temperature and a clock.
• 02The safelight questionWhich colour is safe depends entirely on what the emulsion can see.

• 01Condenser and diffuserTwo ways of getting light through a negative, and the difference in contrast and visible grain.
• 02GrainSilver halide clumps are a physical structure, not a defect, and enlargement is what makes them visible.
• 03The contact sheetThe whole roll at negative size, and the editing that happens with a chinagraph.

• 01Dodging and burningHolding light back or adding it, locally, by hand — the print as an interpretation rather than a readout.
• 02Contrast gradesPaper grade and variable-contrast filtration as the other half of the same decision.

• 01FixingRemoving unexposed halide is what makes the image permanent; incomplete fixing is why prints stain.
• 02Washing and archival lifeResidual thiosulphate is the usual culprit when a print fails decades later.

• 01AutochromeThe Lumière brothers' dyed potato-starch screen, and why the results look like they do.
• 02Three-layer filmKodachrome and its successors, and the colour biases each stock is known for.

• 01Photosites and noiseThe sensor changed the trade-offs rather than ending them; noise replaced grain and behaves differently.
• 02The raw file as a negativeAn unprocessed capture is a set of instructions, like a negative, and the print is still where somebody decides what they meant.