Hi Uwe,
Thanks in advance. One thing I don’t understand, for example, is why Rodinal (http://adox.de/RODINAL.pdf) gives different development times for APX 100 and Retro 100 – surely they’re the same film?
Do you have any information about the Adox films? How do they compare to APX and Kentmere?
How do the Adox developers differ (Rodinal latest formula, Adonal/original formula, APH 09)? And what about Atomal49 – there’s no time specified for APX, only for the Adox films?
Funny, that bit about the instruction sheet. I’ve actually compared the films; they’re identical. No difference, not even the tiniest one, detectable. There were never multiple variants of APX 100. The longer time (8–17 minutes) is the classic one.
Regarding the Rodinal variants: after the war, the Agfa/Wolfen patents were published. Calbe continued to manufacture according to this formula right up to the end and probably still does so today. Since the Agfa brand name was sold to Leverkusen in 1964, the stuff was called R09; that’s how I came to know it in the 1970s. The classic formula had a standard dilution of 1+40 and was already dark black on purchase, as technical chemicals are used. It works nonetheless. I read somewhere that Calbe has increased the concentration in recent years to achieve a standard of 1+50. However, I have never actually held such a bottle in my hand. The original Adonal formula is thought to be one of these two variants.
Agfa/Leverkusen has modified the formula over the years and, in particular, used purified chemicals. However, this has little effect on the development results. Since Agfa’s bankruptcy, the name Rodinal can no longer be used, or at most only to a limited extent. Nevertheless, Rodinal is still produced (‘Rodinal last formula’) and sold under various names. When new, Rodinal is clear to a light pinkish-brown and turns a medium brown over time. Never dark black. The standard dilution has always been 1+50.
Years ago, I once carried out a comparison between Calbe R09 (dark black, standard 1+40) and Agfa Rodinal (1+50). Same film (APX 100), same subject, same lighting. There was a tiny difference in negative density – in other words, a barely detectable difference in the concentration of the active components, or a minimal rounding error to whole minutes, or a minimal variation in my agitation rhythm. That was all. Grain and contrast were identical; the prints were indistinguishable.
Conclusion: pick any one of these models and always use that one (so you don’t get any surprises; see the 1+40/1+50 problem). The results you can achieve are the same.
