Roll 179: While I have given up on shooting expired film from questionable (ebay) sources, I do remain curious about film stocks that are available, just not in 120. A hand roller was looking for interest in Kodak Technical Pan in 120, and I jumped at the opportunity. I have read that Rodinal is not the best choice for this film, but I am a one chemistry kind of guy, so I wanted to check what Rodinal gave me. The internet had its usual recommendations without any kind of data, so I did a test roll using the anecdotes from the internet as guides/guesses.
Developer: Rodinal, 1+95, 10 mL + 950 mL, 20 C, 10 minutes in Simma roller (continuous agitation)
I shot my usual 'square of squares' assuming ISO25, with exposures from -5 stops below normal to +6 above normal exposure along with on blank frame to measure "base + fog". If ISO25 had been the correct film speed, then the exposure 4 stops below normal should have given me a density of 0.09 (0.3 stops darker than "base + fog"). However, I need an extra stop of light to reach that density, so the actual film speed is ISO12. The internet was right about one thing though - Rodinal gives this film a ton of contrast. I get a contrast index of > 1. I will perhaps try a higher dilution or a shorter development time.
I think the flattening of the film curve is because of reciprocity failure. The slow speed of the film, the limited brightness of white light panel, and wanting to shoot at f/6.7 to limit vignetting meant that the last three exposures were 1 s, 2 s, and 4 s in length.
May 04, 2025 at 03:35 PM
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