Response to Rodinal Stock Solution

Dear Craig, I can only speak in respect to "traditional" Rodinal sold as Calbe R09, which has been my standard developer for many years: For one 120 film I mostly add 5ml on 500ml water per film (1:100) and never ever had any problems or signs of exhaustion. The control shots of test charts I occasionally put on films to check how good my system works all give me the same density for midtone and highlight readings. Using this setup I have developed many hundred rolls of film over the years and am absolutely sure that it reliable. I also occasionally use 2,5ml of solution on 500ml (1:200) and it workes just fine. In their R09 data sheet ORWO and later Calbe stated that in 600ml R09 in 1:40 dilution at least six rolls of film can be developed when reused. If my calculation is correct this is about 2,5ml per roll. I would think that this is also a good starting point for R09 as one shot developer. This means: With the 250ml bottle for under $4.- you can develop 100 rolls of film in 1:200 dilution and 50 in 1:100 dilution, making it – according to my knowledge – the cheapest developer on the market with 4c/8c per roll. There is absolutely no need to use more developer in the case of R09. Agfa Rodinal has a different concentration in comparison with R09, but I do think that 10ml per film is "overkill". The "standard" dilution of R09 is stated as 1:40, that of Agfa Rodinal as 1:25. Taking these figures into account 5ml per roll should be ample for Agfa Rodinal. Off course the manufacturers always like to sell more developer.

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