The effect of greater dilution on grainsize and contrast?

Discussion in 'B&W: Film, Paper, Chemistry' started by michielp, May 26, 2007.

  1. michielp

    michielp Member

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    Lately I am wondering what the effect is of greater dilution in the developer on the contrast and the size of the grain of your B&W negative.

    I know that a longer developing time gives more contrast and increases the grain size (correct me if I'm wrong), but what about the effects of greater dilution? What happens to the contrasts and to the grain goin from say 1:25 to 1:50 or to 1:100?

    cheers, mike
     
  2. Anscojohn

    Anscojohn Subscriber

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    Grain size is virtually 100% a function of the level of development, all things being equal. Thus, greater dilution will only decrease apparent grain by decreasing the level of development. the grain will not be decreased if the film is developed to the same density and gamma. That being said, if the grain is sharper because of greater adjacency effects caused by extra dilution, the apparent grain might be subjectively less obtrusive.

    Anscojohn, Mount Vernon, Virginia USA
     
  3. Tom Hoskinson

    Tom Hoskinson Member

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    Film grain size is primarily determined by size and structure of the grains placed in the emulsion by the film manufacturer.
     
  4. percepts

    percepts Member

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    when you start these discussions you should state whether you mean silver grains or grain clumps. For the most part what most people call grain is actually grain clumps. The silver grains migrate into clumps during development. The actual silver grains are minute compared to the grain clump sizes. So what causes clumping? I have no definitive answer to that but I have observed that the higher th PH of the developer, the greater the tendancy of the grain to clump. I know the chemists will argue about this but that is my observation. If grain size is an issue for you, then use Ilford Perceptol or Kodak Microdol X to develop your negatives. You will then have a problem seeing the grain through your grain maginifier because of the lack of clumping that takes place. The grain you see, if you can will be very very fine.
    Use Perceptopl at 1+2 or 1+3 @ 20deg C for appropriate time for your film. About 12mins for HP5 at 1+3. Also Reduce film speed by about 1 stop from iso speed when using either of these developers.
     
  5. dancqu

    dancqu Member

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    [QUOTES=percepts;472925]
    "I have observed that the higher th PH of the developer,
    the greater the tendency of the grain to clump."

    I've not checked specifically for that but have read that
    developer ph is second only to the film itself where grain
    size is concerned.

    "Kodak Microdol X to develop your negatives. You will then
    have a problem seeing the grain through your grain magnifier
    because of the lack of clumping that takes place."

    First place does go to Microdol X for least grain while it
    and Perceptol maintained maximum sharpness. The latter
    slipped a bit on grain. Dilution made little to no difference.
    That from an article by Otis Sprow in Darkroom and Creative
    Camera Techniques. Panatomic X and Agfapan 25 were tested.

    Rodinal developed the most grain; as good though as any
    other for sharpness. If I'm not mistaken, Microdol X is a very
    low ph developer with long developing times. Is it available
    off-the-shelf? I home brew; perhaps a formula? Dan
     
  6. percepts

    percepts Member

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    Assuming Kodak are still making it, then it should be available off the shelf. I use Perceptol for 35mm film as it is readily available in the UK where as Microdol X is not. For 4x5 I use HC110 which is also readily available in the UK.
     
  7. John Bragg

    John Bragg Member

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    Greater dilution in combination with less agitation can produce some very smooth results. There is not nescessarily less grain, just that it looks more refined and less clumpy. This is Tri-X (@ EI 200) in HC-110 Dilution H. 9 mins @ 20c. Agitation continuous for first 30 secs, then 2 gentle inversions at the start of each subsequent minute.Contrast is also held in check by the slight compensation at this dilution.

    http://www.rangefinderforum.com/photopost/showfull.php?photo=63551
     
  8. Tom Hoskinson

    Tom Hoskinson Member

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    Try this Microdol-X substitute recipe, Dan:


    In 1 liter of water dissolve:
    Metol 5 grams
    Sodium Sulfite (anhydrous) 100 grams
    Sodium Chloride (iodine free) 30 grams
     
  9. Anscojohn

    Anscojohn Subscriber

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    That's covered by "all things being equal," as a moment's reflection might make more understandable.

    Anscojohn, Mount Vernon, Virginia USA
     
  10. dancqu

    dancqu Member

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    Included in P. Dignan's Classic B&W Formulas is
    another substitute formula from R. W. Anderson.

    Metol 7.5 grams
    Sodium Sulfite anhydrous 100 grams
    Sodium Bisulfite 7.5 grams
    Water to make 1 liter.

    Almost a D-25. Times and results are the same
    as for Microdol-X. The substitute's weight is not
    the same as the packaged. I doubt that sodium
    chloride will reduce the ph while S. bisulfite
    should some little.

    If one would like to go the ultra-fine grain route via
    low ph and without all that chemistry a bicarbonated
    FX-1 or Beutlers should be worth a try. As with the
    substitutes there likely would be a speed hit. Dan
     
  11. Tom Hoskinson

    Tom Hoskinson Member

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    Yes Dan, I posted R.W.Anderson's substitute formula a long time ago in the APUG recipes section and it caught quite a bit of flack.

    The inclusion of Sodium Chloride is supported by the Microdol-X MSDS.
     
  12. michielp

    michielp Member

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    Thanks everybody, for the remarks. But all of them were about grain size. But what about contrast? What happens to the contrast when you increase the dilution/greater dilution?

    In other words, why would one choose a certain dilution? Why go to a greater one, why go to a larger one?

    Cheers again, Mike
     
  13. argus

    argus Member

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    Michiel,

    contrast is not controlled by dillution but rather by decreasing/increasing development time and agitation.

    G
     
  14. percepts

    percepts Member

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    Yes changing dilution will change contrast.

    If you change from say 1+1 dilution to 1+3 and leave time and temp the same, you will change the effective film speed (reduce) and the characteristic curve shape will also be changed. It tends to rise more slowly (longer toe) and depending on film type, you can introduce a marked shoulder into the film at an earlier point. This is what compensation does. The reverse is also true, i.e. reduce dilution from 1+3 to 1+1 or 1+0 and you will tend towards a shorter toe and shorter shoulder at a higher point.
     
  15. michielp

    michielp Member

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    How do these changes affect the contrast? (I guess I'm not well known to the characteristic curve shapes)

    These changes are when the developing time is left the same, while diluting the solution.

    But what if we change the time accordingly as well? Longer time for higher dilution, and vice versa. So what changes can be expected if one changes the dilution and adjusts the developing time accordingly?
     
  16. percepts

    percepts Member

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    the contrast is not altered evenly along the characteristic curve.

    low contrast would be a flatter curve, longer dynamic range accepted onto film but still fits the paper.

    high contrast would be a steep curve, shorter dynamic range fits on film and still fits to paper.

    contrast is usually measured as gamma which is the average steepness of the curve over its central portion but changing dilution affects both toe and shoulder as well so it affects both shadow contrast and highlight contrast and not just overall contrast.

    The variables are endless which is why you have to test for yourself and arrive at something which suits you. i.e. each dev and film combination combined with temp, agitation and how well you metered, will produce different results. So precise consistency is the name of the game when metering and developing film otherwise your test results will be meaningless.

    changing time may remove most of the effect on toe of the curve but typically you will lose separation between zone 0 and zone 1 when you dilute developer unless you alter time and or film speed to compensate. Time may also increase contrast to negate some of the effect on the shoulder. But once again, it all depends on your film and dev combination etc etc.
     
  17. efreddi

    efreddi Member

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    I can confirm this. Actually I remember that somewhere I have read that this is due to a sort of softening of the gelatine at higher pH so the silver grains are more free to clump together, but I don't know if it's the correct explanation.
    Regards


    Elia
     
  18. percepts

    percepts Member

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    when its gets down to chemistry and no one knows the actual chemical formula of any film or the make up of its gelatin and the vast majority don't know the true chemical formula of the dev they are using or how the reaction process between the unknown film formula and dev formula will take place, its no wonder that there is so much speculation on what any change will do to your results. All you can do is experiment and be very very observant of what happens and keep notes. Film development is not an exact science unless you live and operate inside a vacuum such as a Kodak lab and know exactly what all the parameters are.
     
  19. pentaxuser

    pentaxuser Subscriber

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    Mike. Have a look in the standard gallery at Thomas Krebs " Gottingen 1994". Sorry Thomas my key board doesn't have an umlaut and I've forgotten the ACS11? code for it. He used ID11 at 1:5 which is a dilution I hadn't seen mentioned before. Stock or more often 1:1 is the normal ratio. A couple of us remarked on this and he said that he found it useful in high contrast scenes.

    So high dilution ID11 appeared to work for high contrast scenes. Certainly it was an amazing shot and would make ID11 go a long way.

    pentaxuser
     
  20. fhovie

    fhovie Subscriber

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    Diluting a developer that has 80 to 100 grams of sodium sulfite / liter will always increase the apparant grain size because the solvent action of the sulfite ends when the concentration is cut in half. D76 straight will always look smoother than D76 at 1:3.

    At 1:3 you will get an increase in film speed, sharpness and grain.
     
    Last edited by a moderator: May 31, 2007
  21. percepts

    percepts Member

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    are you sure you meant increase in film speed?
     
  22. fhovie

    fhovie Subscriber

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    Yes - If you read Anchel - it makes sense - the weaker developer (and longer time) has more time to work on the shadows while becoming exhausted in the highlights - this causes more development in the low zones bringing up the film speed.

     
  23. dancqu

    dancqu Member

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    I don't necessarily equate very dilute with weak.
    For example Beutler's and FX-1 are by nature very
    dilute carbonate activated compensating developers.
    They are not weak.

    D23 is a weak developer even though at a 1:3 dilution it
    has four times the amount of metol per liter as FX-1;
    a sulfite activated developer. Dan