Pre and Post Exposure Question

Discussion in 'Exposure Discussion' started by Christoper, Aug 25, 2009.

  1. Christoper

    Christoper Member

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    I have heard about using either a pre or post exposure with color film to control contrast. I would like to try it.

    Has anyone here done this? I need techanical info.

    (Note: I do 4x5 view camera, both positive and negitive color film, I have a Pentax Spotmeter V exposure meter)

    Thanks
     
  2. keithwms

    keithwms Member

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    I have pre-exposed slide film to control contrast, it work well enough. You simply aim it, out of focus, at something uniform and featureless (e.g. the sky, some concrete, a piece of paper) and expose it 3 stops faster than your main exposure will be.

    There is a calibrating gizmo (expodisc), normally used for white-balance control, but you can put one on your lens and preflash with it as well:

    http://www.expoimaging.net/MediaFiles/instructions/EN_16.pdf

    (You could make yourself an expodisc out of something translucent)

    You could also preflash your slide film in the darkroom.

    I never tried preflashing c41 films, since they have so much range anyway. If I really expected problems with contrast I'd simply rate the film at box speed or a wee bit faster, and/or use a graduated neutral density filter, etc....
     
  3. jnanian

    jnanian Advertiser Advertiser

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  4. Christoper

    Christoper Member

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    Thanks guys for the info..
    the APUG forum posts did the trick...