Rodinal: effect of different concentrations

[ymc226]

I want to make sure I have enough developer when I load 2 rolls of 120 per reel in a 5 reel tank so I would want to use Rodinal at 1+25 instead of 1+50.

Besides less time in the tank, what kind of effects on the negative would you expect given the higher concentration of developer?

BTW, as it is not listed on the MDC, can anyone give starting times for Rodinal 1+25 with Fuji Acros exposed at 50. MDC only lists Acros exposed at 125 with a time of 6.75 minutes.

 

[2F/2F]

I'd expect shorter development times, slightly higher contrast, and less visible grain in big enlargements, though maybe hardly any difference with that particular film.

FWIW, you will be OK with 5 mL of Rodinal concentrate per roll. IME, manufacturer's stated minimums can be halved with absolutely no ill effects. This being said, having the same amount per roll that you usually use would probably give you more predictable results without testing first.

 

[Thomas Bertilsson]

If you develop for diffusion enlarging - 5 to 7 minutes depending on lighting conditions.
If you scan or develop for condenser enlarging - 4 to 6 minutes depending on lighting conditions.

You have to do some testing. It won't be perfect right out of the box.

Great film, Acros.

- Thomas

 

[JCJackson]

I have used Rodinal at 1:50 in a 250 ml tank for a single roll of 35mm many times, sometimes with Acros. That works out to 5ml of Rodinal to process a 36 exposure roll (same film area as a 120 roll). Never any problems, so why not use the 1:50 dilution and go with 11 minutes?

 

[john_s]

When a normal developer is diluted, for example D-76 diluted 1+1, there is little more acutance and a little more noticeable grain and a little more film speed, so if Rodinal followed this "rule" your more concentrated dev would produce less grain and less film speed. However, I have read that Rodinal is different in that higher dilutions (1+50 or 1+75) produce less grain, and the explanation given is the relative lack of sulphite in it (so diluting it doesn't have the same effect as with "normal developers," and the very alkaline state of strong Rodinal dilutions like 1+25).

I assume your 120 reels need something like 500mL. My 35mm reels need 250mL. A 36exp roll of 35 film has about the same surface area as a 120 roll. So unless I'm missing something you could use the same dilution of Rodinal that you use for 35mm. Lots of people use 5mL Rodinal + 245mL water = 250mL per 36-exp roll of 35mm.

Agfa's original recommendations which i think were for a minimum amount of concentrate per film of 10mL might have had something to do with their liking for a quite contrasty standard gamma of 0.65 whereas many people today prefer something less unless they're pushing.

 

[ymc226]

Thanks for your recommendations. The Paterson tank I use (35x8 or 120x5) requires 2400 ml of developer. That would be for 10 rolls of 120 as I would load 2 rolls/reel. Currently, if I use Rodinal 1+50, I would use 50ml of Rodinal for an even 5ml/roll. This would be the minimum so for some safety, 1+25 would be 10ml/roll.

I use a VC enlarger and wet print only so I will try 7 minutes first as I do like contrast. Thanks Thomas.

 

[degruyl]

You don't actually need to fill inversion tanks. You just need to get the liquid above the film. That being said: the minimum rodinal required for completion on normally exposed film is about 2.5-3 ml / 8x10 equivalent (135 / 36 exposure, 120, 4 4x5s, etc).

Since you do not want to go to completion, staying above twice that value is a really good idea. In that case, using 1+50 seems to be fine, since the total volume of developer that you are using is freaking huge compared to the film area.

 

[Rolleijoe]

In that same Patterson tank, (since I only shoot 120 now), I mix 1:50 for 10min, and they print perfect on Foma silk papers, and scan equally well into Aperture.