Rodinal dilution and acutance

Discussion in 'B&W: Film, Paper, Chemistry' started by pstake, Mar 29, 2012.

  1. pstake

    pstake Member

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    I have heard it both ways, that higher dilution (i.e.: 1+50) = higher acutance; and that lower dilution (i.e. 1+25) = higher acutance.

    Does anyone know which is correct?
     
  2. cliveh

    cliveh Subscriber

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    Rodinal is a high acutance developer and I would suggest the only difference in dilution strength is that the longer times provide greater possibilities for still bath development, but doubt if this makes much difference.
     
  3. ruilourosa

    ruilourosa Member

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    more of a compensation effect, although semi stand and stand development with 1:100 do indeed increase adjacency effects and makes mackie lines broader and deeper!
     
  4. Richard Jepsen

    Richard Jepsen Member

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    Rodinal at 1:25, especially using Agfa's recommended development times, results in contrasty negatives. One can mistake high contrast for accutance. A properly developed negative using dilutions higher than 1:50 (1:75 and 1:100) produce edge effects enhancing sharpness. The effect is visible but not dramatic. One could argue changing film from Tri-X to FP-4 or T-Max 100 is nearly as effective.
     
  5. pstake

    pstake Member

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    Thanks for this. Thanks to everyone else, too. Good information.
     
  6. George Collier

    George Collier Member

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    +1 on pstake's reply.
    Long development times with high dilutions (a favorite is 1:100, from 20 minutes and up depending on agitation schemes - stand, semi-stand, etc) yield acutance effects.
    The smaller the format size, the more they are seen in the print.
    You can find more on this forum by searching for "stand" and "semi-stand", many threads gone over the dam.
     
  7. pstake

    pstake Member

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    One more question. What is the difference between "stand" and "semi-stand," or is it the same thing?
     
  8. George Collier

    George Collier Member

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    Stand development is a principle that involves initial agitation (longer than normal, some recommend up to 2 minutes), then the tank sits for a much longer than normal time. (not for open tray schemes) Semi stand is similar at the beginning, but introduces agitation at intervals of 3 - 5 minutes, to ensure uniform development in even (eg - sky) areas.
    I have left a lot out here - use the search engine for this forum, and enter the two terms "stand" and "semi-stand". you'll find lots to read, opinion and fact both. People have widely varied experiences with this method.