Base material for the film developer study
The development parameters were chosen to yield density curves that are as similar as possible, i.e. speed and contrast. To determine the ISO speed and the average gamma, see here.
| developer | dilution | time [min] | temperature [C] | ISO effective | Gamma |
|---|---|---|---|---|---|
| Kodak D76 | stock | 9 | 20 | 200 | 0.62 |
| Adox Rodinal | 1+25 | 8 | 22 | 125 | 0.73 |
| Wehner/Alpha | 1+19/1+19 | 9 | 22 | 125 | 0.69 |
| Spur SD2525 | 1+20 | 10 | 20 | 100 | 0.55 |
| Adox FX39 | 1+9 | 7 | 20 | 125 | 0.56 |
| Kodak XTOL | stock | 7 | 20 | 160 | 0.54 |
Density curve (left) and local contrast (right) as a function of exposure. A difference of ΔE=0.3 corresponds to one f-stop..
Central area of the siemens star transferred to the film. The grey circles mark the resolution limit determined from the spectrum of the spatial frequencies, as indicated in the caption. For two circles, the outer circle marks the resolution limit caused by a loss of contrast due to broadening of the dark stripes (halo). The exposure of all stars is chosen so that the dark stripes on the outside (2 LP/mm) have a density of D=1.
Area around the 8 LP/mm (grey arc) of the Siemens star transferred to film. The edge sharpness (DP, definition parameter) determined from the spatial frequency spectrum is given in the image heading; DP=1 corresponds to optimal edge sharpness.
MikroskopbildeThe visible grain structure of the film-developer combinations, arranged in order of decreasing RMS granularity (GRMS). How this is defined and determined, see here. The yellow circles mark the size of the ‘visual structure size’, the image width is approx. 0.75 mm of the negative.