The results of my Pebble Project tests to date now have a gallery. You will find it under the 'Resources' section of this site's menu. It puts all the results in one place, and offers both film scans and darkroom prints. You can click on each individual image for a larger version. Any further results that I share in blog posts will be added here too. I hope this will make the gallery a useful resource.
If you have been tuning in to this project, you will notice that I have added some scans and prints of other film and developer combinations. The addition of HP5+ and Delta 100 Professional here suggest the structure of my thinking for films to explore.
If you are mainly interested in the visual aspect of the tests, you may want to head over to the gallery now to take a look. What follows are some technical details and corrections for those interested in such matters, or who want to actively use the recipes explored.
When making the darkroom prints, I was able to standardise at contrast grade 2.5 and aperture f5.6. I used Ilford's Multigrade paper. It was not possible to print every negative for the same time, of course, due to differing exposures and hence negative densities. This then demands a standardisation procedure, and inevitably judgements - my personal judgements - come into play. I decided to print to the first hint of very pale, 'almost white' tone in the central lower small stone. I plan to do some tests with Multigrade Warmtone, which will necessitate changes in exposure times once again due to the different ISO of the paper (roughly half the speed of 'standard' Multigrade).
Adjustments and errors
I came up with quite a list originally with which to offer some interpretations of my first results (grain, midtone contrast, sharpness, and so on). The list itself was good, but I am now a little more philosophical about the comparisons.
Allowing for the fact that these are my results made with my own conditions and equipment (the old zone system caveat of the individual nature of test results), it strikes me now that tonality is the most obvious category of general applicability. The tonal comparisons that the gallery has to offer are broadly good, and I would expect you to get results not unlike mine if you followed the same film and developer recipes.
Making inkjet prints from scans adds variables that are different from darkroom printing variables. Because I am somebody who makes both inkjet and darkroom prints from negatives, I wanted to explore both processes. Comparing darkroom prints to inkjet ones provided an object lesson in the role of the printer drivers and scanner. One could argue that comparisons of grain, sharpness and midtone contrast are still good within, but not across, systems (be it digital setup or darkroom).
I was already aware that exposure variations would impact on tonality. I took the decision to expose the Perceptol samples differently, for example, because it is a speed reducing developer. This is in line with normal exposure practice. Put differently, there is no universal standard of exposure even following ISO in a studio situation. As the zone system teaches, ISO is nothing but a starting point for an individual's exposure value. That said, I exposed the FP4+ sample at 100 ISO, which in box speed terms is a little additional exposure. The Delta 100 sample was similarly exposed at 100, thus making it slightly less exposed by comparison. This can be seen in the negatives. I have ruminated somewhat as to whether to continue to expose Delta 100 at 100, or to give it the extra exposure in line with FP4+.
Lastly, I must declare a good old fashioned mistake. I adjusted aperture in order to change the exposure (as mentioned in the Perceptol sample), but neglected to take this into account when thinking about sharpness and grain. The problem is that, when comparing samples containing aperture and thus exposure differences, you are looking first at differences in aperture, and only second at the role of the developer. Other than making more convoluted adjustments to the lighting strength (and thus introducing a new set of variations), I'm not sure how this can be avoided. Better to look on sharpness differences with this in mind.