As a matter of personal clarity and discipline I have devised a description formula that applies where a picture of one of my photographs can be seen but the physical reality of the photograph cannot itself be inspected. The commonest occasion for this is when I post an electronic file derived from the scan of a photograph. Here is a recent example from flickr:
Late Fall, Lake Jindabyne
Gelatin-silver photograph on Ultrafine Silver Eagle VC FB photographic paper, image size 21.3cm X 16.4cm, from a Fomapan 400 4x5 negative exposed in a Tachihara 45GF double extension field view camera fitted with a Schneider Super Angulon 75mm f5.6 lens and a #25 red filter.
Titled and signed recto, stamped and annotated verso.
That, I reckon, just about says it all and succinctly too.