KRST and 4x5 film

Discussion in 'B&W: Film, Paper, Chemistry' started by BrianPhotog, Jun 14, 2009.

  1. BrianPhotog

    BrianPhotog Member

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    Shooting ERA 100 and HP5+ 4x5 sheets...

    What's a good dilute and time for KRST to bump shadow detail definition and contrast?

    Does temp matter?

    Thanks!
     
  2. haryanto

    haryanto Member

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    I use KRST 1:2 for 2-3 minute, I noticed that KRST dont enhance the shadow area much
    but more in the highlight
     
  3. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I use 1+3 for about 8 min at room temperature to bump up the highlights about one zone usually.
     
  4. Doremus Scudder

    Doremus Scudder Member

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    Don't rely on selenium toning to compensate for underexposed or otherwise improperly processed negatives. You should refine your exposure and development to give you the shadow detail and contrast index you want.

    Then, when you have the occasional negative that needs a skosh more contrast overall, you can use selenium intensification to achieve this. You should not, however, make this a basic part of your film processing scheme!

    I use KRST at a 1+2 dilution for 5 minutes (more seems to have no further effect, but it won't hurt since the negs tone to "completion") to get a Zone expansion of about one zone. The shadows are not significantly affected, rather the toner intensifies the negative proportionally, with the highlights getting the most added density, the shadows the least. Selenium intensification will not give you more film speed or compensate for underexposure.

    Temperature matters in all chemical reactions: colder = slower, warmer = faster. However, with selenium intensification of negatives one usually tones to completion, so the exact temperature is not critical if you allow adequate time for the toning to take place. Room temperature should be alright unless you live in an igloo...

    Note: selenium intensification does not work on pyro-developed negatives as it removes the stain, taking away contrast. The net result is about zero. There may be some way to selenium tone pyro negs and then re-activate the stain, but I do not know of one.

    Best,

    Doremus Scudder

    Best
     
  5. Vaughn

    Vaughn Subscriber

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    I will agree that selenium toner will not "save" a underexposed negative. Perhaps a little better neg can be drawn out of one that has been underdeveloped, but one still needs silver on the negative to be toned.

    I have taken a well exposed (if not a touch over-exposed) and developed neg, and to increase the contrast for alt printing processes have bleached the neg slightly to reduce the lower values and then selenium toned it to push the highlight values. That works nicely.

    Tone in a white tray helps to see the the effects while toning -- I just tone (1:3) until I do not see anymore density increase.

    Vaughn
     
  6. BrianPhotog

    BrianPhotog Member

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    Great!

    I know it's not a neg saver (there are better processes if that's what I'm after).

    Thanks guys!