es. I refer to the objects and light sources, jointly, as the 'photographed objects'. ii. A photographic event occurs. The photo-sensitive object undergoes material changes when it is exposed, for a particular period of time, to light from the photographed objects. The new material properties are preserved in a form that constitutes a record of the photographic event. iii. The material changes in the photo-sensitive object produce, or make it possible to produce, a photograph: a photo-object which displays a photo-image.18 The technique for early Daguerreotypes fulfils the process with the following steps: a polished metal plate is coated with photo-sensitive chemicals. During the photographic event, chemicals react to light by hardening onto the plate. To produce a visible image, chemicals must be washed off the plate, revealing only the hardened deposits. 17 See Phillips, D. (2009) 'Photographs and Causation: Responding to Scruton's Scepticism' for further elaboration of this account. 18 A photograph is necessarily the product of the photographic process, but not every product of this process displays a visual image. Cf. fn. 15. DAWN M. PHILLIPS 11 Modern digital cameras fulfil the process differently: the photo-sensitive object is an electronic sensor. During the photographic event, individual photon-sensors react to light by building up electrical charge. The electrical charge is registered and stored as binary code. Computer processing converts the code to produce visual images which can be screened or printed. The defining step of the process is the occurrence of a photographic event. It is important not to conflate the photographic event with the photograph. A photograph has a causal history that definitively depends on a photographic event. A photographic event is not itself an object – the event is the recording of light, which produces a record. Sometimes the record of the photographic event is used as the photo-object (as with a Daguerreotype). Sometimes the record of the event is used to produce sep