Learning Photography Course - 9. Film

Module 9 of the Learning Photography Course: film, from the crystal to the print.

What film physically is: a clear base, an emulsion of silver halide crystals, and the latent image that exists only as chemical change until a developer makes it visible. Why grain is not noise, and why film ISO is a property of the film, measured under ISO 6:1993 at a density 0.1 above base plus fog. Formats from half-frame and 35 mm (24 × 36 mm, ISO 1007) to 120 and sheet film. Loading without ruining a roll, and why negative and slide film need opposite exposure instincts.

Processing, with every figure taken from the manufacturers' own documents. Black-and-white: Ilford HP5 Plus in ID-11 at 20 °C, seven and a half minutes at EI 400 and fourteen minutes pushed two stops to EI 1600, with Ilford's own agitation and wash method. C-41 from Kodak Z-131: a developer held to 37.8 ± 0.15 °C for 3:15, while every later step is allowed 24 to 41 °C, and why that one tolerance decides the colour. E-6 from Kodak Z-119: a first developer held to five seconds and 0.2 °C, and Kodak's own push of Ektachrome E100 to eight minutes. Cross-processing, and why no manufacturer publishes data for it.

The darkroom: Ilford's safelight limits, test strips, Multigrade's twelve filters from 00 to 5, dodging and burning, and resin-coated against fibre-based paper, with Ilford's wash sequences.

Reciprocity failure, worked from Ilford's own formula: HP5 Plus at a metered ten seconds needs 20.4 seconds, which Ilford rounds to twenty. And the honest case for and against film, with no nostalgia.

Educational documentary. Not financial or investment advice.