In large part these appear to have been made using photographs as a
reference by using tracing paper and a biro to transfer outlines, and then
working on the plate entirely by hand. One of the things I was wondering
looking at these was whether it was possible to use a controlled etching
process on the rocked mezzotint place with a variable thickness gelatine
layer to transfer a photograph - the etching should smooth the surface by
removing the peaks in a similar way to burnishing, thus lightening the
tone.
I've not come across anyone doing this - but it is an area of printmaking
that I'm not well-informed in, so I'd be interested to hear more.
Also in Cambridge - at Kettles Yard until 1 March - are some extremely
large photograms made on stream beds and in the sea at night using both
conventional silver materials and Cibachrome - worth a look.
Peter Marshall
On Fixing Shadows and elsewhere:
http://www.people.virginia.edu/~ds8s
Family Pictures, German Indications, London demonstrations &
The Buildings of London etc: http://www.spelthorne.ac.uk/pm/