|Ilford G.30 Chromatic backed plates|
For the first test I metered for 10 ISO, and took three successive exposures on the same plate, progressively withdrawing the darkslide between each shot (although not very evenly). Viewed from left to right, this effectively achieved exposures indexes of 10, 5, and 2.5. The plate was stand-developed in R09 One Shot (Rodinal), at a dilution of 1:100 for one hour, with a couple of inversions at the half hour mark.
|Ilford G.30 Plate test - three successive exposures at 10 EI|
I subsequently shot two plates at night with long exposures. On first inspection, these seemed like they might have been over-exposed, but, particularly with the second plate below, this was important to register the foreground detail, although at the expense of the clarity of the lit-up lettering. The haloes around the lights are somewhat unusual, this may be due to the fact it's shot on glass. It is also noticeable that there's a line of thicker emulsion at two of the adjacent edges where, as it was poured onto the plate, the emulsion collected as the excess was poured off.
|Ilford G.30 Plate - 1 minute exposure at f5.6|
|Ilford G.30 Plate - 2mins exposure at f5.6|
As a result of my research into Ilford, I discovered the Ilford Technical Information Book, which contains a sheet on the G.30 Chromatic plates, dated to 1965. This provides additional information for the plates from the leaflet in the box. It describes the G.30 Plate as
widely used for the photo-micrography of metal specimens. It is particularly useful for green-corrected microscope lenses since it allows comparatively short exposures to be given when using a Tricolour Green filter.
Ilford G.30 Chromatic Plates are used in the graphic arts, copying and scientific fields. For graphic arts work the main use is in the preparation of continuous tone negatives.It gives the ASA setting for tungsten lighting as 5, against the daylight setting of 10. The date of the technical information sheet disproves the idea above after my first test that the meter settings were from before the change in speed ratings for black & white emulsions, and so the plates have lost very little sensitivity since they were made nearly 50 years ago. The table of development times gives further dilutions and times for both continuous and intermittent agitation.
|Ilford G.30 Chromatic Plate development times|
|Ilford G.30 Chromatic Plate sensitometric curves|
|Ilford G.30 Plate, 12 seconds exposure at f4.5|