under exposed

Discussion in 'Black and White' started by jim_ryder, Sep 1, 1997.

  1. White hostas in a garden in early morning. Gray card read F45 for 5min with 100 speed tmax rated at 25. I remembered reciprocity failure factor to 9 minutes but forgot the bellows extension factor which after the exposure I realized would have doubled the time. The hostas will look brillant but I am worried about the leaves and other shadow detail. My normal TMax developer time is usually about 5min. The whole point is for a rich dark gray background with no highlights, rich detail. How should I proceed?
     
  2. Did you take spot readings of the shadows? If they were more than about 3 stops below the gray card, you will have lost the detail.

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    Kodak say, on reciprocity failure, that 10 seconds should be increased to 15s, and 100s increased to 200s (for T-Max 100).

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    So your 5 minutes (300s) should have been increased to something more than 600s (10 minutes).

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    On development, they suggest 6 min in T-Max at 24 deg C. You say you normally use 5 min.

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    Increasing development by about 40% will raise the film speed by about 1 stop, but will also increase contrast. You might try using a more dilute developer to reduce the contrast, which will also require greater development times. 1+9 for 22 minutes at 24 deg C might be a good starting point.

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    If these pictures are important to you, you should do tests first. Simulate the original subject (eg with gray and white paper), shoot it, and develop. Examine the negatives for shadow detail. Adjust as necessary. When happy, develop your original roll.
     
  3. Alan: Thanks for your response. The information from Kodak is very helpful. I will try a longer development time but I wonder how much it will affect the low density areas. Your idea about testing first is a good one.The contrast in the picture will be with the blooms and the background. "A white lady in a dark forest". I think overall my very conservative "rating" of the film, I set my meter at 25, will save me on this one. But I need to be more carerful.
     
  4. Jim: If you develop longer, you just get more highlight
    density; you can't develop shadow detail. 'Expose for shadows,
    Develop for highlights.' I suspect you may be getting unreliable
    exposure readings, or misinterpreting the reciprosity curve.
    Foilage reflects a lot of infra-red radiation, but film is not
    very sensitive to IR. The bad news: light meters read IR very
    well. This leads to underexposed foilage which is usually placed
    on zone III, right where we read our basic exposure. Developing
    time for brightness range expansion or contraction is
    determined by the placement of zone VII.
    Meters are not sensitive to UV, but film is! (Alway use a UV filter!)
    Luckily there is one meter that reads light the same way film 'sees' it. Zone VI Studios
    (available through Calumet) modifies Pentax spot meters to 'see'
    like Tri-X. See 'Camera & Darkroom) April 93, p.51.
    Or maybe you can get a Zone VI catalogue from Calumet.
     
  5. Jim: ERROR: Should have read "...zone VIII" not zone VII.
    This screen is very hard to use because of no word wrap.
    Maybe someone will fix it. Hint hint!!
     
  6. Michael: Wow. thanks that all makes sense to me. The one thing I might note is I use a Kodak gray card to make my readings. I double check the foliage with the meter but I usually trust the gray card reading.I can't imagine giving up my meter which I know and love for anything else. I am one of those who believe in making the most skilled use of existing, known, equipment. Your information about IR definetely will make me more skilled. Your point about needing to expose for the low densities is what I thought.
     

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